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Cue-recognition mechanisms and person perception Park, Justin H. 2006

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CUE-RECOGNITION M E C H A N I S M S A N D PERSON PERCEPTION  by JUSTIN H . P A R K B.Sc, The University of Alberta, 2000 M . A . , The University of British Columbia, 2002  A THESIS SUBMITTED IN P A R T I A L F U L F I L L M E N T OF THE REQUIREMENTS FOR THE D E G R E E OF DOCTOR OF PHILOSOPHY in THE F A C U L T Y OF G R A D U A T E STUDIES (PSYCHOLOGY)  T H E UNIVERSITY OF BRITISH C O L U M B I A October 2005  © Justin H . Park, 2005  11  Abstract  Our different responses to different individuals depend on psychological mechanisms that detect specific kinds of people and produce context-appropriate cognitions and emotions. These mechanisms often respond to heuristic cues (e.g., symmetry) that may signal some underlying information (e.g., health). Many cue-recognition mechanisms may be usefully understood as evolved adaptations that served specific functions in ancestral environments. These mechanisms may operate in a wide range of situations in contemporary contexts, which may help us better understand many aspects of social cognition. In this dissertation, I describe mechanisms of kin recognition and parasite recognition, and I describe empirical studies that tested some of the implications of these mechanisms. One study tested the hypothesis that attitude similarity may serve as a heuristic kinship cue. The results showed that the perception of an attitudinally similar other may activate kinship-relevant cognitions, which may enhance prosocial motivations. A second study tested the hypothesis that physical disabilities may serve as a heuristic parasite cue. Although the results showed that disabilities may activate disease-relevant cognitions, the evidence for the hypothesis was not strong. Finally, a set of studies tested the hypothesis that obesity may serve as a heuristic parasite cue. The results showed that people may be especially motivated to avoid physical (versus nonphysical) contact with obese individuals; that chronically heightened concerns about parasites are positively correlated with dislike of fat people; and that the perception of obesity may activate disease-relevant cognitions, especially when the threat of parasites has been made salient. I discuss some of the broader implications as well as the methodological limitations.  iii Table of Contents Abstract : Table of Contents List of Tables List of Figures Acknowledgements Co-Authorship Statement : Introduction.. Chapter 1. Cue-Recognition Mechanisms 1.1. Introduction 1.2. Features of Evolved Psychological Mechanisms 1.3. The Signal-Detection Problem and Recognition Errors 1.4. Functional Flexibility of Cue-Recognition Mechanisms 1.5. Heuristic and Reflective Processes 1.6. Conclusion 1.7. References Chapter 2. Kin-Recognition Mechanisms 2.1. Introduction 2.2. Adaptive Context of K i n Recognition 2.3. Kinship Cues 2.4. Functional Cognitions and Emotions 2.5. Recognition Errors 2.6. Functional Flexibility 2.7. Heuristic and Reflective Processes 2.8. Conclusion 2.9. References Chapter 3. Empirical Test: Attitude Similarity as a Cue for Kinship 3.1. Introduction 3.2. Overview of Study and Specific Hypotheses 3.3. Method 3.4. Results 3.5. Discussion 3.6. Broader Implications of Kin-Recognition Mechanisms 3.6.1. Empathy and altruism 3.6.2. Interpersonal processes 3.6.3. Morality 3.7. Conclusion 3.8. References Chapter 4. Parasite-Recognition Mechanisms 4.1. Introduction 4.2. Adaptive Context of Parasite. Recognition 4.3. Parasite Cues 4.4. Functional Cognitions and Emotions 4.5. Recognition Errors 4.6. Functional Flexibility 4.7. Heuristic and Reflective Processes 4.8. Conclusion 4.9. References  • •  ii iii • v vi • vii .....viii 1 4 -.4 4 7 9 11 12 13 16 16 16 -17 20 21 22 23 24 24 31 ••• 31 32 35 38 40 43 44 44 46 47 47 52 52 52 54 55 58 59 60 61 61  Chapter 5. Empirical Test: Physical Disabilities as a Cue for Parasites 67 5.1. Introduction 67 5.2. Overview of Study and Specific Hypotheses 69 5.3. Method 70 5.4. Results : '. 73 5.5. Discussion 75 5.6. Conclusion 77 5.7. References 78 Chapter 6. Empirical Test: Obesity as a Cue for Parasites 80 6.1. Introduction 80 6.2. Overview of Studies and Specific Hypotheses 81 6.3. Part 1: Physical versus Nonphysical Avoidance 82 6.3.1. Method 82 6.3.2. Results .' 84 6.3.3. Discussion 86 6.4. Part 2: Concerns about Parasites and Dislike of Fat People 87 6.4.1. Method 88 6.4.2. Results 89 6.4.3. Discussion 91 6.5. Part 3: Implicit Associations between Fat and Disease 92 6.5.1. Method 93 6.5.2. Results 94 6.5.3. Discussion 96 6.6. General Discussion 98 6.7. Broader Implications of Parasite-Recognition Mechanisms 99 6.8. Conclusion 100 6.9. References 101 Chapter 7. Summary and Some Final Thoughts 104 7.1. Summary of Empirical Findings 104 7.1.1. Attitude similarity as a cue for kinship 104 7.1.2. Physical disabilities as a cue for parasites 105 7.1.3. Obesity as a cue for parasites 105 7.1.4. Implications of the empirical findings 106 7.2. Additional Issues and Questions 107 7.2.1. Kin-recognition mechanisms 108 7.2.2. Parasite-recognition mechanisms 110 7.2.3. Universality of evolved mechanisms : 112 7.3. Conclusion 113 7.4. References 113 Appendix A . Faith in Intuition Scale 115 Appendix B. Attitudes Questionnaire (High Heritability) 116 Appendix C. Attitudes Questionnaire (Low Heritability) 117 Appendix D. Questions about Elaine and Carol 118 Appendix E. Perceived Vulnerability to Disease Scale .119 Appendix F. Belief in a Dangerous World Scale 121 Appendix G. Disgust Sensitivity Scale 122 Appendix H . Sample Page of Questionnaire: Physical/Nonphysical Avoidance .... 124 Appendix I. Anti-Fat Attitudes Scale 126  List of Tables Table 5.1. Correlations between Vulnerability Variables and I A T effects (European Participants) •'. 74 Table 5.2. Correlations between Vulnerability Variables and IAT effects (East Asian Participants) .....75 Table 6.1. Feelings of Discomfort in Situations Involving Physical and Nonphysical Contact . 85 Table 6.2. Results of A l l 2 x 2 Analyses of Variance: The Interaction Effects  86  Table 6.3. Correlations between Germ-Aversion P V D and Dislike of Fat Peopie ..89  VI  List of Figures Figure 1.1. Schematic diagram of an evolved psychological mechanism  4  Figure 1.2. Impact of regulatory variables on cue-recognition mechanisms  10  Figure 3.1. Regression lines indicating predictive effects of Faith in Intuition on implicit associations linking similar other to family and to pleasant 39 Figure 6.1. Regression lines indicating predictive effects.of Perceived Vulnerability to Disease (Germ-Aversion Subscale) on dislike of fat people, in the pictures-present and pictures-absent conditions 90 Figure 6.2. Effect of slide-show manipulation on implicit associations linking fat people to disease (fat-disease IAT) and to unpleasant (fat-unpleasant IAT) 95  Acknowledgements  I am indebted to Mark Schaller for his guidance and support throughout my graduate studies. I could not have asked for a better mentor. I also thank my family and friends for their support and encouragement.  viii Co-Authorship Statement  I am the primary author on all the work presented in this thesis. The research was conducted in collaboration with my research supervisor Mark Schaller. Other collaborators include Jason Faulkner, Chris Crandall, and Lesley Duncan. I played a major role in designing the research, conducting the research, and analyzing the data. I played the primary role in the manuscript preparation.  1 Introduction  Why do we feel comfortable among familiar people and uneasy among strangers? Why are we quicker to help some people than others? Why do we value attractive people, and, on the flip side, why do we stigmatize people who appear unusual? These sorts of questions reveal our natural propensity to react differently to different kinds of people. Of course, such propensity requires the ability to perceptually distinguish different kinds of people in the first place. We usually take this ability for granted because it normally goes unnoticed: Without much effort, we quickly and effortlessly recognize and react to different kinds of individuals. But our subjective experience is misleading. Our effortless perception of people is in fact an outcome of complex psychological mechanisms that discern a number of subtle cues. The perception of these cues automatically activates specific thoughts and feelings that not only tell us whom we are dealing with, but facilitate context-appropriate actions. We can appreciate the automaticity of this perceptual process by trying to verbalize it. For example, try to articulate how you know that certain faces are attractive. It isn't easy. Only recently have scientists documented the cues—such as symmetry and "averageness"—that contribute to facial attractiveness. But we rarely think about these cues when we look at faces; within a fraction of a second, we just know when we see an attractive face. This self-evident inference is the product of complex psychological mechanisms that respond to subtle cues. Such cue-recognition mechanisms are the subject of this dissertation. Social cognition often begins with the perception of cues, so understanding the nature of cue-recognition mechanisms is an important task for psychologists. As I hope to illustrate in this dissertation, the operation of cue-recognition mechanisms can have  2 some interesting and unexpected consequences, which may help us better understand many psychological phenomena. There may be practical implications as well. We may discover that our automatic reactions to people are sometimes entirely irrational and—in the case of negative reactions—potentially damaging. On the other hand, identifying mechanisms that facilitate positive reactions may provide us with tools to create positive interpersonal environments. To begin the inquiry, there are several questions that we need to address. What are some of the important cue-recognition mechanisms that are involved in everyday social cognition? What are the origins and functions of these cue-recognition mechanisms? What features serve as cues, and why? What higher-level psychological processes are triggered by the perception of these cues? These are difficult questions, and thus, a unifying framework may be helpful. I draw on the evolutionary psychological perspective to provide that framework. This framework is useful for understanding many previous research findings relevant to cue recognition; it also provides logical tools for generating novel hypotheses concerning the operation of cue-recognition mechanisms. Accordingly, I review previous research findings and situate them within this framework; I also describe new empirical research that tested some of the novel hypotheses. The basic tenet of the evolutionary perspective is that many complex psychological mechanisms exist because they enhanced reproductive fitness for ancestral humans. Many adaptive problems confronted ancestral humans, and distinct cuerecognition mechanism may have evolved to deal with different problems. I focus on two adaptive problems and the associated mechanisms. One adaptive problem is recognizing genetic kin; the other is recognizing parasite carriers. Although these are  3 very different problems, a common set of logical principles can be applied to both kinrecognition and parasite-recognition mechanisms. This dissertation is organized as follows. Chapter 1 introduces the evolutionary approach to understanding evolved cue-recognition mechanisms. Chapter 2 describes the adaptive problem of kin recognition and the mechanisms that may have evolved to solve this problem. There is a substantial literature documenting kin-recognition mechanisms—not necessarily of humans specifically, but of animals in general—and there are several implications for how people may perceive other individuals. Chapter 3 describes a study that I conducted to test one implication of kin-recognition mechanisms—specifically, the hypothesis that attitude similarity may serve as a heuristic cue for kinship. Chapter 4 describes the adaptive problem of parasite recognition and the mechanisms that may have evolved to solve this problem. Although little research has documented parasite-recognition mechanisms in humans, some of the research findings on stigmatization are consistent with the operation of parasite-recognition mechanisms; and there are further implications of parasite-recognition mechanisms concerning how people may perceive other individuals. Chapter 5 describes a study that I conducted to test one implication—specifically, the hypothesis that physical disabilities may serve as a heuristic cue for parasites. Chapter 6 describes a set of studies that I conducted to test another implication—specifically, the hypothesis that obesity may serve as a heuristic cue for parasites. Chapter 7 includes sections in which I summarize the empirical findings, discuss critically the theoretical framework, and highlight additional issues and questions concerning cue-recognition mechanisms.  4 Chapter 1. Cue-Recognition Mechanisms  1.1. Introduction Evolved psychological mechanisms can be investigated by following a set of logical steps. By articulating the adaptive problems that likely confronted ancestral humans, various psychological mechanisms and their design features can be conjectured. Based on these design features and other assumptions regarding ancestral environments, specific hypotheses concerning the operation of these mechanisms can then be deduced. These hypotheses specify the external stimuli that may be relevant to the mechanisms, the distinct physiological and psychological responses that may be activated by these stimuli, and the conditions under which such activation may be especially likely to occur. Tests of such hypotheses may therefore yield research findings that may illuminate everyday social cognitive phenomena. In the rest of this chapter, I highlight the key features and principles of evolved cue-recognition mechanisms.  1.2. Features of Evolved Psychological Mechanisms To investigate evolved psychological mechanisms, a specific set of components must be articulated, including (a) some fitness-relevant cue, (b) functional cognitions and emotions that may be activated by the cue, and (c) adaptive behavior (see Figure 1.1). A cue is typically a stimulus (e.g , sweet taste of fruit) that was correlated with some ;  fitness-relevant attribute (e.g., ripeness of fruit) over evolutionary time. Because of the  FitnessRelevant Cue  Functional Cognitions and Emotions  Adaptive Behavior  Figure 1.1. Schematic diagram of an evolved psychological mechanism.  5 fitness relevance of such attributes (e.g., there are nutritional benefits associated with eating ripe fruit), there may be evolved responses to the associated cues (e.g., preference for sweet tastes). Functional cognitions may include inferences about people or situations, activation of semantic concepts related to people or situations, or other cognitive processes that steer behavior. Emotions have been recognized for their role in motivating adaptive action. In a major review of research on emotions, Zajonc (1998) noted, "The capacity for emotional reaction, thus, is the capacity to discriminate between and to respond adaptively to present and anticipated conditions that are likely to be harmful or beneficial to the individual or his/her community (p. 592, emphases in the original). Within the evolutionary perspective, emotions have been conceptualized as systems that organize and motivate adaptive behavior (LeDoux, 1996; Nesse, 1990). It has been argued that psychological mechanisms are numerous and domain specific (at least to some extent), because there is neither a general adaptive problem nor a general adaptive solution (Buss, 1995; Tooby & Cosmides, 1992). For instance, solutions to the problem of avoiding parasites are different from solutions to the problem of helping genetic kin. It's unlikely, therefore, that the same mechanism underlies both kin recognition and parasite recognition. In addition to domain specificity, additional characteristics of evolved psychological mechanisms have been articulated. In their discussion of the evolution of the fear module, Ohman and Mineka (2001) outlined four characteristics in particular: selectivity, automaticity, encapsulation, and specialized neural circuitry. These are directly relevant to cue-recognition mechanisms. Selectivity implies sensitivity to stimuli that have been correlated with fitnessrelevant attributes over evolutionary time. The principle of selectivity explains, for instance, why people more readily develop phobias of snakes than automobiles, even though automobiles pose a much greater threat to safety among most contemporary  6 human populations (harmful snakes, but not automobiles, were part of the environments in which humans evolved). Just as humans are quick to associate snake-like shapes with danger, humans may be prepared to associate many other stimuli with fitness-relevant attributes. Automaticity implies that "behavioral modules that have a deep evolutionary origin typically are not under voluntary control but are directly elicited by stimuli" (Ohman & Mineka, 2001, p. 485). For example, the perception of a danger-connoting cue (e.g., snake) quickly and effortlessly activates functional responses (e.g., fear), which in turn motivate adaptive behavior (e.g., escape); no rational decision-making process is required to activate this fearful response. Encapsulation implies that mechanisms are cognitively impenetrable. That is, once a cue-recognition mechanism is triggered, the ensuing responses (cognitive inferences, emotions) may be generally inaccessible to conscious processes. For example, when we perceive attractive faces, we have little access to or control over the inferential processes underlying that perception. But control may be exerted in subsequent steps, including steps that are involved in producing actual behavior (therefore, the perception of a cue does not mandatorily lead to behavior). The principles of automaticity and encapsulation have implications for research methods as well: Examinations of cuerecognition mechanisms may require methods and measures that can capture automatic and encapsulated responses. Finally, evolved mechanisms may be associated with specialized neural circuitry. The burgeoning area of cognitive neuroscience is starting to document specific neural regions whose activities correspond to specific cognitive and emotional processes, some of which can be situated within the framework of evolved psychological mechanisms.  7 The basic components of cue-recognition mechanisms are straightforward. The perception of a fitness-relevant cue may activate functional cognitions and emotions, which may enhance the likelihood that a particular behavior will be performed. There may be additional characteristics of evolved mechanisms, such as selectivity, automaticity, encapsulation, and specialized neural circuitry; I revisit these in chapter 7.  1.3. The Signal-Detection Problem and Recognition Errors One particular challenge confronts perceptual mechanisms that use superficial cues as signals for deeper attributes: The correlation between cues and attributes is rarely perfect. Some apparent cues signal nothing, and some attributes do not produce perceptible cues. Moreover, recognition systems are not infallible detectors of cues themselves. A n inevitable consequence is that perceivers will sometimes make errors concerning the presence or absence of some fitness-relevant attribute. This is an instance of the signal-detection problem. In the terminology of signal detection theory, two specific types of errors may occur: When the recognition system responds in the absence of a true signal, this is called a false-positive error; when the system fails to respond although a signal is present, this is called a false-negative error. From a rational perspective, having an equal amount of false-positive and falsenegative errors may seem to be the optimal solution. (Though errors in general are inevitable, the relative error rates can be adjusted by tinkering with the reactivity of mechanisms to cues: High reactivity produces more false-positive errors, and low reactivity produces more false-negative errors.) From a functional perspective, however, the costs associated with these two types of errors are rarely equivalent (Haselton & Buss, 2000; Nesse, 2005).  8 A n illustrative example is the smoke detector, a mechanism designed to respond to smoke (cue) that is correlated with harmful fires (signal). Because this correlation is not perfect, and because smoke detection itself may sometimes fail, recognition errors are inevitable. For a person relying on a smoke detector for safety, false-positive errors (false alarms in the presence of benign smoke) and false-negative errors (no alarm in the presence of actual harmful fire) are not equivalent. It's much safer to have an overreactive, false-alarm-prone smoke detector than to have an underreactive one that may miss actual fires. Biological cue-recognition mechanisms are often confronted with similar dilemmas. And although organisms may not deliberately choose one type of error over the other, natural selection may choose for them. It's likely that, over the course of evolution, cue-recognition mechanisms have evolved toward making errors that are less costly in terms of reproductive fitness (for further discussion on the smoke detector principle, see Nesse, 2005). This logic has been applied to different kinds of recognition mechanisms, and it has been argued that the optimal solution—in terms of reproductive fitness—is to be biased toward making one type of error over the other (Haselton & Buss, 2000; Kurzban & Leary, 2001; Ohman & Mineka, 2001). The signal-detection problem isn't the only reason for recognition errors. Even i f a perfect correlation existed between cues and signals, recognition errors may still occur if organisms encounter novel, unnatural situations. Human psychological mechanisms evolved in ancestral environments that were very different from contemporary environments. In the world we inhabit today, a wide range of stimuli may trigger cuerecognition mechanisms, even though they don't actually correspond to any adaptive signal. The fear module, for instance, responds to snake-like and spider-like shapes (Ohman & Mineka, 2001). In modern contexts, realistic-looking rubber snakes and plastic spiders that are obviously benign may nevertheless trigger, i f only briefly, a  9 fearful response. Such recognition errors are found in social perception as well, with less trivial consequences. For instance, humans seem to be prepared to quickly categorize others according to coalitional alliances and thus are sensitive to superficial cues that may signal group membership (e.g., speech patterns, clothing, cultural rituals; Kurzban & Leary, 2001). In contemporary multiethnic societies—which are an evolutionary novelty—superficial features such as skin color may also trigger this mechanism, resulting in the tendency to readily categorize and mistrust people on the basis of "race" (Kurzban, Tooby, & Cosmides, 2001). These sorts of recognition errors may be fairly common, and they represent instances of a broader tendency for evolutionarily novel contexts to produce nonadaptive or maladaptive behaviors. For example, it has been suggested that many common maladies (e.g., depression, cancer, overeating) may be attributed to discrepancies between ancestral and modern environments (Buss, 2000; Nesse & Williams, 1994; Pinel, Assanand, & Lehman, 2000). In sum, not only are cue-recognition mechanisms naturally error prone, but they may get derailed in unnatural contexts. A key implication is that evolved cue-recognition mechanisms may be operating in a much wider range of circumstances than those for which they were designed. A l l of the studies that I conducted in this dissertation examined potential false-positive errors of cue-recognition mechanisms.  1.4. Functional Flexibility of Cue-Recognition Mechanisms Evolved psychological mechanisms may operate automatically, but they do not always operate inyariantly. They may be influenced by regulatory information pertaining to the costs and benefits associated with particular responses. Environments in which organisms evolved were typically not static for a species, but varied because of local ecology, seasonal variations, and other contextual factors—factors that may have  10 influenced the extent to which specific adaptive responses were indeed adaptive. Consequently, organisms may have evolved to be sensitive to such environmental variation. As a simple example, ostriches that are feeding alone spend approximately one-third of their time looking up and scanning for predators—a behavioral tendency that confers adaptive benefits. But as the number of other ostriches in the vicinity increases— which increases the likelihood that one of them will be scanning at any given time—each individual spends much less time scanning and, as a result, more time feeding (Bertram, 1980). Evolved cue-recognition mechanisms may be functionally flexible in response to various kinds of regulatory information found in the developmental context, in the local ecological context, within the individual, and in the immediate context (see Figure 1.2). I discuss these in turn. The notion of evolved psychological mechanisms does not imply that organisms enter the world with a fixed set of psychological mechanisms. Rather, it implies that organisms may be prepared to learn certain things especially quickly; thus, all evolved mechanisms necessarily depend on environmental input. The developmental context may influence cue-recognition mechanisms in several ways. For example, even the paradigmatic fear module may involve learning processes in which specific stimuli (e.g., snake-like shape) become associated with fitness-relevant information (e.g., danger)— although the learning occurs very quickly and may not even require conscious perception  Ecological and Ontogenetic Influences  Individual and Contextual Variables  FitnessRelevant Cue  1  Functional Cognitions and Emotions  Adaptive Behavior  Figure 1.2. Impact of regulatory variables on cue-recognition mechanisms.  11 of the snake (Ohman & Mineka, 2003). The ecological context may play an important role in determining which stimuli serve as fitness-relevant cues. For instance, cues that reliably signal fitness-relevant attributes in some contexts may not be equally reliable in others. Here's a simple example: If you grew up in an environment in which you and your family members shared the same hair color, you may then be particularly sensitive to hair color as a cue for kinship; but if you and your family members had different hair colors, you may find hair color to be a useless feature for kin recognition. For humans, learning processes implicate cultural influences and possible cross-cultural differences. Of course, cross-cultural differences are not inconsistent with evolved psychological mechanisms. Because many evolved mechanisms depend on contextual input, they may manifest differently within different human populations. Functional flexibility is also observed in the day-to-day operation of psychological mechanisms. Evolved psychological responses are often beneficial, but they impose costs as well, which may be in the form of energy, time, and inattention to other stimuli. As a result, psychological mechanisms may have evolved to be sensitive to cost-benefit information and to be more readily activated when the information suggests that the benefits outweigh the costs. This information may be internal or external to the organism. Internal variables such as sex, age, and ovulatory cycle may influence the operation of evolved psychological mechanisms (e.g., Daly & Wilson, 1990; Gangestad. & Thornhill, 1998), as may external variables such as availability of resources, group size, and ambient darkness (e.g., Bertram, 1980; Schaller, Park, & Mueller, 2003).  1.5. Heuristic and Reflective Processes The mind is not a bundle of automatic stimulus-response mechanisms; we do sometimes exert control over our behavior. To some extent, controlled processes can be  12 empirically distinguished from automatic ones (Wegner & Bargh, 1998). In general, automatic processes involve little conscious awareness and require only modest cognitive resources. On the other hand, controlled processes usually involve conscious awareness and require more cognitive resources. In laboratory contexts, controlled—but not automatic—processes are disrupted by other tasks that also require cognitive resources. Given that evolved cue-recognition mechanisms may operate largely automatically, any controlled processes that may simultaneously be involved in person perception should be identified. Also, the relationship between automatic and controlled person-perception processes should be clarified. A n interesting observation is that controlled processes may be more evolutionarily recent than automatic ones; indeed, many of the controlled processes are uniquely human (Geary, 2005). It has been argued that the distinction between these two kinds of psychological processes is fundamental to human cognition (Geary, 2005; Pinker, 1997). Indeed, empirical investigations have commonly discovered these two kinds of processes (for examples in social psychology, see Chaiken & Trope, 1999). Typically, one kind of process is described as operating heuristically and automatically (outside of conscious awareness and control), whereas the other kind of process is described as operating reflectively and in a rule-based manner (Strack & Deutsch, 2004). It's possible that the relative prominence of these two kinds of processes depends on local context, resulting in observed cultural differences in how people make inferences (e.g., Norenzayan, Smith, Kim & Nisbett, 2002).  1.6. Conclusion A number of cue-recognition mechanisms have been investigated by following the principles outlined above. These mechanisms include components for recognition of  13 fitness-relevant cues, for activation of functional cognitions and emotions, and for production of adaptive behavior. The logical principles specify when and why recognition errors may arise and suggest ways in which cue-recognition mechanisms may be influenced by additional variables. In subsequent chapters, I apply these principles to specific adaptive problems and allied cue-recognition mechanisms, and I describe studies that tested some of the implications.  1.7. References Bertram, B. C. R. (1980). Vigilance and group size in ostriches. Animal Behaviour, 28, 278-286. Buss, D. M . (1995). Evolutionary psychology: A new paradigm for psychological science. Psychological Inquiry, 6, 1-30. Buss, D. M . (2000). The evolution of happiness. American Psychologist, 55, 15-23. Chaiken, S., & Trope, Y . (Eds.). (1999). Dual-process theories in social psychology. New York: Guilford. Daly, M . , & Wilson, M . (1990). Killing the competition: Female/female and male/male homicide. Human Nature, 1, 81-107. Gangestad, S. W., & Thornhill, R. (1998). Menstrual cycle variation in women's preferences for the scent of symmetrical men. Proceedings of the Royal Society of London B, 265, 927-933. Geary, D. C. (2005). The origin of mind: Evolution of brain, cognition, and general intelligence. Washington, DC: A P A . Haselton, M . G., & Buss, D. M . (2000). Error management theory: A new perspective on biases in cross-sex mind reading. Journal of Personality and Social Psychology, 78, 81-91.  14 Kurzban, R., & Leary, M . R. (2001). Evolutionary origins of somatization: The functions of social exclusion. Psychological Bulletin, 127, 187-208. Kurzban, R., Tooby, J., & Cosmides, L. (2001). Can race be erased? Coalitional computation and social categorization. Proceedings of the National Academy of Sciences, 98, 15387-15392. LeDoux, J. (1996). The emotional brain: The mysterious underpinnings of emotional life. New York: Simon & Schuster. Nesse, R. M . (1990). Evolutionary explanations of emotions. Human Nature, 1, 261-289. Nesse, R. M . (2005). Natural selection and the regulation of defenses: A signal detection analysis of the smoke detector principle. Evolution and Human Behavior, 26, 88105. Nesse, R. M . , & Williams, G. C. (1994). Why we get sick: The new science of Darwinian medicine. New York: Times Books. Norenzayan, A., Smith, E. E., Kim, B. J., & Nisbett, R. E. (2002). Cultural preferences for formal versus intuitive reasoning. Cognitive Science, 26, 653-684. Ohman, A., & Mineka, S. (2001). Fear, phobia, and preparedness: Toward an evolved module of fear and fear learning. Psychological Review, 108, 483-522. Ohman, A., & Mineka, S. (2003). The malicious serpent: Snakes as a prototypical stimulus for an evolved module of fear. Current Directions in Psychological Science, 12, 5-9. Pinel, J. P. J., Assanand, S., & Lehman, D. R. (2000). Hunger, eating, and ill health. American Psychologist, 55, 1105-1116. Pinker, S. (1997). How the mind works. New York: Norton.  Schaller, M . , Park, J. H., & Mueller, A . (2003). Fear of the dark: Interactive effects of beliefs about danger and ambient darkness on ethnic stereotypes. Personality and Social Psychology Bulletin, 29, 637-649. Strack, F., & Deutsch, R. (2004). Reflective and impulsive determinants of social behavior. Personality and Social Psychology Review, 8, 220-247. Tooby, J., & Cosmides, L. (1992). The psychological foundations of culture. In J. H . Barkow, L. Cosmides, & J. Tooby (Eds.), The adapted mind: Evolutionary psychology and the generation of culture (pp. 19-136). New York: Oxford University Press. Wegner, D. M . , & Bargh, J. A . (1998). Control and automaticity in social life. In D. T. Gilbert, S. T. Fiske, & G. Lindzey (Eds.), The handbook of social psychology (4th ed., pp. 446-496). New York: McGraw-Hill. Zajonc, R. B. (1998). Emotions. In D. T. Gilbert, S. T. Fiske, & G. Lindzey (Eds.), The handbook of social psychology (4th ed., pp. 591-632). New York: McGraw-Hill.  16 Chapter 2. Kin-Recognition Mechanisms  2.1. Introduction Different social interactions may have different fitness consequences for many animals; thus, animals may have evolved the ability to recognize different kinds of conspecifics. For instance, humans tend to categorize others especially quickly on the basis of sex, age, and race (Fiske & Neuberg, 1990). Another variable along which people readily discriminate others is kinship. We generally know who is kin and who isn't, and we treat people very differently on this basis. Such behavioral discrimination may reflect evolved psychological mechanisms that discern cues for kinship and produce appropriate responses. As noted in the previous chapter, specific adaptive problems must be articulated to investigate kin-recognition mechanisms. There are many adaptive problems that may have contributed to the evolution of kin-recognition mechanisms (e.g., incest avoidance, selective inhibition of aggression). I focus on just one of these:.the problem of nepotism.  2.2. Adaptive Context of Kin Recognition The fact that many species of animals frequently engage in altruistic behavior has been a major challenge for evolutionary biology, because genes that motivate individuals to sacrifice themselves for others should not be retained in populations. However, several theories suggest that some altruistic acts may enhance the reproductive fitness of individuals (e.g., Axelrod & Hamilton, 1981; McAndrew, 2000). Hamilton's (1964) kin selection theory articulates one important process through which altruism could have evolved. In essence, because close kin have a high probability of sharing genes by virtue of common descent, any genes that motivated individuals to help close kin may have  17 propagated copies of themselves in genetic relatives. Furthermore, because the probability of propagating copies of such genes is higher between closer kin than between more distant kin (probabilities that can be easily calculated), the ability to discern degree of relatedness may also have been selected. The logic of kin selection theory, it has been argued, demonstrates that gene-based "help-my-kin" algorithms are evolutionarily stable adaptations among social species (Daly, Salmon, & Wilson, 1997; Dawkins, 1989). Indeed, studies of altruistic behavior confirm the basic tenets of kin 1  selection theory: Both human and nonhuman animals tend to assist those that are more closely related to them (e.g., Burnstein, Crandall, & Kitayama, 1994; Sherman, 1977). So how do individual organisms distinguish kin from nonkin? Animals appear to recognize kin by attending to superficial cues that were correlated with degrees of kinship during evolutionary history (Rendall, 2004). What cues do nonhuman animals use to recognize kin? Do humans use similar cues? Research shows that there is substantial overlap in heuristic kin-recognition mechanisms between human and nonhuman animals; thus, they are discussed together in the following section.  2.3. Kinship Cues Research has identified two broad classes of kinship cues. One of these pertains not to specific features of individuals, but to spatial location and early association. Many species of animals rely on spatial proximity as a cue for kinship. As Konrad Lorenz discovered, goslings imprint on a spatially proximate animal, which usually—but not always—happens to be their mother. Many species of birds treat any chick in their nest To clarify a common misunderstanding, nepotism has little to do with genetic similarity. The idea that organisms favor genetically similar others is a useful but misleading heuristic. Rather, nepotism is the result of a specific set of gene-based altruistic algorithms that spread in populations because they happened to reside in the bodies of close kin. For more on this issue, see Daly et al. (1997) and Dawkins (1989). 1  18 as their own, sometimes feeding parasitic chicks as a result (Winfree, 1999). Spatial location and association are used as cues to infer kinship in species such as honeybees, ants, sea lions, lambs, pigs, and hyenas (Downs & Ratnieks, 1999; Hanggi & Schusterman, 1990; Porter, Desire, Bon, & Orgeur, 2001; Puppe, 1998; Singer & Espelie, 1998; Wahaj et al., 2004). In many primate species, the inference of kinship depends substantially on the extent to which one has lived in proximity to another individual for a prolonged period, especially during childhood (Rendall, 2004). Based on her work on chimpanzees, Goodall (1986) noted the following: Attitudes toward kin are shaped, to a large extent, by the degree offamiliarity of the individuals concerned, and depend on close and prolonged association. It is only logical, therefore, that helping behaviors will on occasion be extended to familiar individuals even when they are not very close kin. (p. 380, emphases in the original) Humans also appear to rely substantially on early association as a cue for kinship. People who grow up together seem to sense a degree of kinship despite conscious knowledge that they are genetically unrelated, and as a result, find each other unattractive as sexual partners—a phenomenon known as the Westermarck effect (Shepher, 1971; Van den Berghe, 1983). The length of coresidence appears to be critical to this effect. There is evidence that incest is more likely to occur between family members who have not coresided for significant amounts of time (Bevc & Silverman, 2000). In addition, people who have coresided with opposite-sex siblings for a longer time are more likely to judge others' incestuous acts as morally wrong, suggesting that coresidence plays an important role in tuning kinship-relevant cognitions and emotions (Fessler & Navarette, 2004; Lieberman, Tooby, & Cosmides, 2003). Coresidence influences nepotistic tendencies as well. When families break up and fathers are separated from their children, the level of  19 continued paternal investment is predicted by the length of prior coresidence; when stepfamilies form, stepfathers' investment in stepchildren is predicted by how early their coresidence began (Anderson, Kaplan, & Lancaster, 1999). For various reasons, spatial location and association do not always serve as reliable kinship cues. There is, however, another class of kin-recognition mechanism that involves perceptual phenotype matching—a process in which phenotypic features of target individuals are compared against a "kin prototype" (Hauber & Sherman, 2001). Birds seem to use similarity in vocalizations to recognize kin (Sharp, McGowan, Wood, & Hatchwell, 2005). In many mammalian species, individuals are sensitive to the odors of others, which they may use to discriminate kin and nonkin (e.g., Mateo & Johnston, 2000). There is evidence suggesting that humans too may use olfactory similarity to detect kin (Porter & Moore, 1981; Weisfeld, Czilli, Phillips, Gall, & Lichtman, 2003). This makes sense, given that genetically related kin may actually smell more like each other: One study found that individuals were able to match odors of unfamiliar mothers and offspring (Porter, Cernoch, & Balogh, 1985). Primates may use visual cues as well. Chimpanzees, for instance, are able to match unfamiliar female chimpanzees with their offspring on the basis of facial features (Parr & de Waal, 1999). Whether chimpanzees are able to compare others' facial features with their own is unclear, but the ability to match others' facial features could nevertheless be useful for kin recognition (e.g., one could compare unknown individuals with known kin). Facial similarity may serve as a particularly strong kinship cue for humans: There is evidence that fathers favor children that look more like them (Apicella & Marlowe, 2004; Burch & Gallup, 2000), and people generally report greater willingness to assist unrelated children who happen to have facial features in common with their own (DeBruine, 2004; Platek, Burch, Panyavin, Wasserman, & Gallup, 2002). A recent study provided compelling evidence that facial  20 similarity serves as a kinship cue (DeBruine, 2005): When looking at opposite-sex target faces that were manipulated to be similar to or different from their own, participants indicated that the similar faces were more trustworthy (consistent with nepotism), but less attractive as relationship partners (consistent with incest avoidance). People may use additional superficial similarities as kinship cues. For instance, people are more likely to assist someone who shares their name—especially if the shared name is perceived as uncommon (Oates & Wilson, 2002). More broadly, terms such as fraternity, brotherhood, and soul sisters are often used to arouse emotions normally reserved for kin, suggesting that they may also serve as kinship cues (Salmon, 1998).  2.4. Functional Cognitions and Emotions If one function of kin recognition is to facilitate nepotism, then the perception of kinship cues may automatically activate functional cognitions and emotions that motivate nepotism. So what are some of the functional cognitions? There is evidence that nonhuman primates are able to represent kin as a distinct conceptual category (Cheney & Seyfarth, 1990). There is also evidence that young children are prepared to quickly learn the consequences of biological descent—for instance, young children infer that genetic relatives are more likely to share physical (e.g., height) than nonphysical (e.g., belief) properties (Springer, 1992). Furthermore, it's possible that the perception of kinship cues automatically activates semantic concepts associated with kinship. More research has documented the emotions (and emotion-like experiences) that may be relevant to nepotism. The experience of attachment may be one of them (Bowlby, 1982). Feelings of subjective closeness may also serve this function: Research shows that genetically related individuals arouse subjective feelings of closeness, and people's willingness to help kin is mediated in part by this subjective experience (Korchmaros &  !  21 Kenny, 2001). People also demonstrate greater trust in individuals who are facially similar to them (DeBruine, 2002), and people's willingness to help others is predicted by their feelings of "oneness" with the recipients (Maner et al., 2002). Another emotion-like experience that may motivate nepotism is empathy. The ability to empathize appears to be primitive: Human and nonhuman primates observing conspeciftcs display neural and physiological responses that reflect the targets' experiences (Carr, Iacoboni, Dubeau, Mazziotta, & Lenzi, 2003; Levenson & Ruef, 1992). Moreover, it has been argued that empathy evolved, in part, to motivate altruistic behavior toward kin (Krebs, 1987; Preston & de Waal, 2002; Schaller, 2003). If empathy is associated with kin recognition, then it should be triggered in response to hypothesized kinship cues (e.g., similarity). Indeed, many studies have demonstrated the impact of similarity on physiological and verbal indicators of empathy (Batson, Duncan, Ackerman, Buckley, & Birch, 1981; Krebs, 1975). The link between perceived similarity and empathy appears to be automatic (i.e., requires little cognitive resource): Empathic responses to similar others (but not dissimilar others) is uninterrupted by mental fatigue (Nelson, Klein, & Irvin, 2003). There is also evidence that physical symptoms of empathy (e.g., empathic blushing) occur more between friends—who are more familiar with and similar to each other—than between strangers (Shearn, Spellman, Straley, Meirick, & Stryker, 1999). And individuals with higher trait empathy are especially likely to respond favorably to attitudinally similar others (Grover & Brockner, 1989).  2.5. Recognition Errors Because kin recognition depends on superficial cues, recognition errors are inevitable. If any bias exists at all, kin-recognition mechanisms may be biased toward false-positive errors, responding to a relatively wide range of kinship cues (and  22 occasionally helping nonkin). This is because the costs associated with occasionally helping nonkin are likely to be offset by the costs associated with false-negative errors (not helping actual kin) and the benefits associated with correct identification (helping kin). (For discussion and a specific example, see Lotem, Nakamura, & Zahavi, 1995.) This bias may, of course, depend on additional contextual variables, such as the costs of helping behavior and the relative prevalence of kin in the environment (see Agrawal, 2001; Reeve, 1998). Kin-recognition errors are more likely to occur in unnatural contexts. In fact, many kin-recognition mechanisms (e.g., imprinting in goslings, the Westermarck effect) were discovered as a result of errors that occurred in unnatural situations. Also, experiments that investigate the role of facial similarity as a kinship cue often employ a method in which participants' faces are morphed with target faces—which amounts to creating an artificial kinship cue and assessing recognition errors (e.g., DeBruine, 2005). The ubiquity of documented false-positive errors in kin recognition suggests that a wide range of superficial similarities may serve as heuristic kinship cues, and thus, individuals may automatically respond to nonkin as kin without realizing it.  2.6. Functional Flexibility Functional responses to kinship cues are not invariant. As noted in the previous chapter, cue-recognition mechanisms may be sensitive to additional fitness-relevant information. Developmental experiences may attune the reactivity of individuals' kinrecognition mechanisms. For instance, growing up among a large group of kin may lower the response threshold for these mechanisms such that individuals are more reactive to kinship cues later in life. Also, growing up among kin with a specific—and unique—phenotypic feature may sensitize individuals to that particular feature as a  kinship cue. Other individual-level variables may also moderate kin-recognition mechanisms. For instance, men may be more sensitive to kinship cues than are women, possibly as a result of paternity uncertainty (Platek et al., 2002, 2004). There is also evidence that adults with children—whose kin-recognition mechanisms are in "overdrive"—are generally more nepotistic (Neyer & Lang, 2003).  2.7. Heuristic and Reflective Processes Of course, human kin recognition does not depend entirely on heuristic processes. As with many other judgments and inferences, both heuristic and reflective processes may be involved. Our intuitions about kinship provide some clues. In general, our reflective thoughts about kinship seem to be distinct from the cue-based inferences: At a rational level, we rarely confuse people who happen to be familiar or similar to us with actual kin. In addition, people in all cultures employ elaborate kinship rules to understand how people are related (Brown, 1991)—rules that may differ across cultures but share universal features (Jones, 2004). Because the heuristic and reflective processes operate independently, we may be aware that a person with whom we grew up is not actual genetic kin (as in the case of adoptive families), but nevertheless experience kinrelevant cognitions and emotions (e.g., the Westermarck effect). In most natural situations, heuristic and reflective processes may yield the same inferences. But they may sometimes diverge. When confronted with nonkin bearing kinship cues, the evolutionary ancient heuristic mechanisms may automatically activate kin-relevant cognitions and emotions, even though the reflective inferences clearly indicate otherwise.  24 2.8. Conclusion The widespread tendency to engage in nepotistic action is predicated largely upon a set of cue-based kin-recognition mechanisms. To a significant extent, these mechanisms operate independently of any rational assessments of genetic relatedness. A n interesting implication is that the perception of kinship cues—in the absence of any reflective thoughts about kinship—may automatically activate cognitions and emotions that increase the tendency to engage in prosoeial behavior. In the next chapter, I describe a study that addressed one specific question: Does attitude similarity serve as a heuristic cue for kinship?  2.9. References Agrawal, A . F. (2001). K i n recognition and the evolution of altruism. 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Kenrick (Eds.), Evolutionary social psychology (pp. 265-296). Mahwah, NJ: Erlbaum. Dawkins, R. (1989). The selfish gene (New ed.). Oxford: Oxford University Press. DeBruine, L. M . (2002). Facial resemblance enhances trust. Proceedings of the Royal Society of London B, 269, 1307-1312. DeBruine, L. M . (2004). Resemblance to self increases the appeal of child faces to both men and women. Evolution and Human Behavior, 25, 142-154.  26 DeBruine, L. M . (2005). Trustworthy but not lust-worthy: Context-specific effects of facial resemblance. Proceedings of the Royal Society of London B, 272, 919-922. Downs, S. G., & Ratnieks, F. L . W. (1999). Recognition of conspecifics by honeybee guards uses nonheritable cues acquired in the adult stage. Animal Behaviour, 58,. 643-648. Fessler, D. M . T., & Navarrete, C. D. (2004). Third-party attitudes toward sibling incest: Evidence for Westermarck's hypotheses. Evolution and Human Behavior, 25, 277-294. Fiske, S. T., & Neuberg, S. L. (1990). A continuum of impression formation, from category-based to individuating processes: Influences of information and motivation on attention and interpretation. Advances in Experimental Social Psychology, 23, 1-74. Goodall, J. (1986). The chimpanzees of Gombe: Patterns of behavior. Cambridge, M A : Harvard University Press. Grover, S. L., & Brockner, J. (1989). Empathy and the relationship between attitudinal similarity and attraction. Journal of Research in Personality, 23, 469-479. Hamilton, W. D. (1964). The genetical evolution of social behaviour. Journal of Theoretical Biology, 7, 1-52. Hanggi, E. B., & Schusterman, R. J. (1990). Kin recognition in captive California sea lions {Zalophus californianus). Journal of Comparative Psychology, 104, 368372. Hauber, M . E., & Sherman, P. W. (2001). Self-referent phenotype matching: Theoretical considerations and empirical evidence. Trends in Neurosciences, 24, 609-616. Jones, D. (2004). The universal psychology of kinship: Evidence from language. Trends in Cognitive Sciences, 8, 211-215.  27 Korchmaros, J. D., & Kenny, D. A . (2001). Emotional closeness as a mediator of the effect of genetic relatedness on altruism. Psychological Science, 12, 262-265. Krebs, D. (1975). Empathy and altruism. Journal of Personality and Social Psychology, 32, 1134-1146. Krebs, D. (1987). The challenge of altruism in biology and psychology. In C. Crawford, M . Smith, & D. Krebs (Eds.), Sociobiology and psychology: Ideas, issues, and applications (pp. 81-118). Hillsdale, NJ: Erlbaum. Levenson, R. W., & Ruef, A . M . (1992). Empathy: A physiological substrate. Journal of Personality and Social Psychology, 63, 234—246. Lieberman, D., Tooby, J., & Cosmides, L. (2003). Does morality have a biological basis? A n empirical test of the factors governing moral sentiments regarding incest. Proceedings of the Royal Society of London B, 270, 819-826. Lotem, A., Nakamura, H., & Zahavi, A. (1995). Constraints on egg discrimination and cuckoo-host co-evolution. Animal Behaviour, 49, 1185-1209. Maner, J. K., Luce, C. L., Neuberg, S. L., Cialdini, R. B., Brown, S., & Sagarin, B. J. (2002). The effects of perspective taking on motivations for helping: Still no evidence for altruism. Personality and Social Psychology Bulletin, 28, 1601-1610. Mateo, J. M . , & Johnston, R. E. (2000). K i n recognition and the 'armpit effect': Evidence of self-referent phenotype matching. Proceedings of the Royal Society of London B, 267, 695-700. McAndrew, F. T. (2002). New evolutionary perspectives on altruism: Multilevelselection and costly-signaling theories. Current Directions in Psychological Science, 11, 79-82.  28 Nelson, D. W., Klein, C. T. F., & Irvin, J. E. (2003). Motivational antecedents of empathy: Inhibiting effects of fatigue. Basic and Applied Social Psychology, 25, 37-50. Neyer, F. J., & Lang, F. R. (2003). Blood is thicker than water: Kinship orientation across adulthood. Journal of Personality and Social Psychology, 84, 310-321. Oates, K , & Wilson, M . (2002). Nominal kinship cues facilitate altruism. Proceedings of the Royal Society of London B, 269, 105-109. Parr, L. A., & de Waal, F. B. M . (1999). Visual kin recognition in chimpanzees. Nature, 399, 647-648. Platek, S. M . , Burch, R. L., Panyavin, I. S., Wasserman, B . H., & Gallup, G. G., Jr. (2002). Reactions to children's faces resemblance affects males more than females. Evolution and Human Behavior, 23, 159-166. Platek, S. M . , Raines, D. M . , Gallup, G. G., Jr., Mohamed, F. B., Thomson, J. W., Myers, T. E., et al. (2004). Reactions to children's faces: Males are more affected by resemblance than females are, and so are their brains. Evolution and Human Behavior, 25, 394-405. Porter, R. H., Cernoch, J. M . , & Balogh, R. D. (1985). Odor signatures and kin recognition. Physiology and Behavior, 34, 445—448. Porter, R. H., Desire, L., Bon, R., & Orgeur, P. (2001). The role of familiarity in the development of social recognition by lambs. Behaviour, 755,207-219. Porter, R. H., & Moore, J. D. (1981). Human kin recognition by olfactory cues. Physiology and Behavior, 27, 493-495. Preston, S. D., & de Waal, F. B . M . (2002). Empathy: Its ultimate and proximate bases. Behavioral and Brain Sciences, 25, 1-72.  29 Puppe, B. (1998). Effects of familiarity and relatedness on agonistic pair relationships in newly mixed domestic pigs. Applied Animal Behaviour Science, 58, 233-239. Reeve, H. K . (1998). Acting for the good of others: Kinship and reciprocity with some new twists. In C. Crawford & D. L . Krebs (Eds.), Handbook of evolutionary psychology: Ideas, issues, and applications (pp. 43-85). Mahwah, NJ: Erlbaum. Rendall, D. (2004). "Recognizing" kin: Mechanisms, media, minds, modules, and muddles. In B. Chapais & C. M . Berman (Eds.), Kinship and behavior in primates (pp.295-316). Oxford: Oxford University Press. Salmon, C. A . (1998). The evocative nature of kin terminology in political rhetoric. Politics and the Life Sciences, 17, 51-57. Schaller, M . (2003). Ancestral environments and motivated social perception: Goal-like blasts from the evolutionary past. In S. J. Spencer, S. Fein, M . P. Zanna, & J. M . Olson (Eds.), Motivated social perception: The Ontario Symposium (pp. 215-231). Mahwah, NJ: Erlbaum. Sharp, S. P., McGowan, A., Wood, M . J., & Hatchwell, B. J. (2005). Learned kin recognition cues in a social bird. Nature, 434, 1127-1130. Shearn, D., Spellman, L., Straley, B., Meirick, J., & Stryker, K . (1999). Empathic blushing in friends and strangers. Motivation and Emotion, 23, 307-316. Shepher, J. (1971). Mate selection among second generation kibbutz adolescents and adults: Incest avoidance and negative imprinting. Archives of Sexual Behavior, 1, 293-307. Sherman, P. W. (1977). Nepotism and the evolution of alarm calls. Science, 197, 1246— 1253.  30 Singer, T. L., & Espelie, K . E. (1998). Nest and nestmate recognition by a fungusgrowing ant, Apterostigma collare Emery (Hymenoptera: Formicidae). Ethology, 104, 929-939. Springer, K . (1992). Children's awareness of the biological implications of kinship. Child Development, 63, 950-959. Van den Berghe, P. L . (1983). Human inbreeding avoidance: Culture in nature. Behavioral and Brain Sciences, 6, 91-123. Wahaj, S. A., Van Horn, R. C , Van Horn, T. L., Dreyer, R., Hilgris, R., Schwarz, J., et al. (2004). K i n discrimination in the spotted hyena (Crocuta crocuta): Nepotism among siblings. Behavioral Ecology and Sociobiology, 56, 237-247. Weisfeld, G. E., Czilli, T., Phillips, K . A., Gall, J. A., & Lichtman, C. M . (2003). Possible olfaction-based mechanisms in human kin recognition and inbreeding avoidance. Journal of Experimental Child Psychology, 85, 279-295. Winfree, R. (1999). Cuckoos, cowbirds and the persistence of brood parasitism. Trends in Ecology and Evolution, 14, 338-343.  31 Chapter 3. Empirical Test: Attitude Similarity as a Cue for Kinship  2  3.1. Introduction Research on kin-recognition mechanisms suggests that many phenotypic similarities may serve as heuristic kinship cues, including similarities in odors, facial features, and names. In the study described in this chapter, I explored the possibility that attitude similarity may serve as a kinship cue. This hypothesis is plausible for a couple of reasons. First, research shows that many attitudes are heritable; to some extent, individual differences in attitudes are phenotypic manifestations of underlying genetic differences (e.g., Olson, Vernon, Harris, & Jang, 2001). This means that, on average, closely related individuals tend to have more highly similar attitudes by virtue of their genetic relation. One implication is that attitudes higher in heritability may be better kinship cues. (As specific examples, attitudes toward the death penalty tend to be more highly heritable than attitudes toward separate gender roles.) Consistent with this reasoning, the tendency to respond favorably to attitudinally similar others tends to be stronger for attitudes that are higher in heritability (Tesser, 1993). Second, even in the absence of an evolved tendency to rely specifically on attitude similarity as a kinship cue, humans may be innately prepared to learn to employ any reliable similarity as a rough indicator of kinship. And given that family members tend to have similar attitudes (because of heritability and shared environment), it may make sense to use such similarity as a kinship cue.  A version of this chapter has been published separately: Park, J. H., & Schaller, M . (2005). Does attitude similarity serve as a heuristic cue for kinship? Evidence of an implicit cognitive association. Evolution and  2  Human Behavior, 26, 158-170.  32 There is another reason to speculate that attitude similarity may serve as a kinship cue. Research has shown that people often respond favorably toward attitudinally similar others, which parallels responses to actual kin. For instance, perceived attitude similarity is associated with greater levels of liking and positive affect (e.g., Byrne et al., 1971; Chen & Kenrick, 2002). Perceived similarity in attitudes and other traits is also associated with higher levels of empathy and prosocial behavior (e.g., Batson, Duncan, Ackerman, Buckley, & Birch, 1981; Krebs, 1975). Given this commonly observed link between attitude similarity and prosocial tendencies, evidence documenting a link between attitude similarity and kin-recognition responses (and between kin-recognition responses and prosocial tendencies) may elucidate a previously undocumented link between evolved nepotistic tendencies and contemporary prosocial behavior.  3.2. Overview of Study and Specific Hypotheses Evidence consistent with the hypothesized kin-recognition process can be obtained if perceivers respond more positively to similar targets than to dissimilar ones (e.g., DeBruine, 2002; Oates & Wilson, 2002). However, evidence of a positive response by itself does not unequivocally support the activation of psychological mechanisms pertaining to kinship, because similarity may produce positive responses for conceptually distinct reasons. More direct evidence supporting the hypothesis requires the measurement of responses that are not merely positive, but more specific to the concept of kinship. In the present study, participants were introduced to two unknown target individuals. One individual was depicted as attitudinally similar to the participants, and the other was depicted as dissimilar. A n implicit measure was then used to assess the extent to which participants differentially associated these two target individuals with  33 kinship-relevant concepts. The implicit measure was a reaction-time method called the Implicit Association Test (IAT; Greenwald, McGhee, & Schwartz, 1998). The IAT has been used in previous research to assess implicit cognitive associations between social categories (e.g., Black) and semantic concepts (e.g., unpleasant). The rationale for using the IAT in the present study was this: If the perception of a kinship cue (e.g., similarity) automatically activates kinship concepts (e.g., family), this may be captured by measuring the strength of implicit associations between these categories. Accordingly, an IAT task was designed to assess the extent to which the attitudinally similar target person (relative to the dissimilar target person) was implicitly linked to the semantic concept "family." If indeed attitude similarity serves as a kinship cue, then there should be evidence of this cognitive linkage (Hypothesis 1). It's possible, however, for the similar-family linkage to emerge spuriously, as the result of psychological responses that are conceptually irrelevant to kinship. The semantic concept "family" surely has a positive connotation, and similar others may arouse positive thoughts for a variety of reasons. Indeed, high degrees of similarity in attitudes have been observed not only among family members, but also between spouses and between friends (Rushton & Bons, 2005). Consequently, a tendency to link the concept "family" to the similar target person could result indirectly, as a byproduct of a more immediate tendency to associate the similar target person with pleasant thoughts of a nonspecific nature. Participants thus completed a second IAT task that assessed the extent to which the similar target person (relative to the dissimilar target person) was implicitly linked to a broader class of pleasant concepts. It's possible that attitude similarity serves as a cue for kinship (which is the conceptual hypothesis investigated here); but—for conceptually distinct reasons— attitude similarity may also serve as a cue for other kinds of close relationships (e.g.,  34 spouse, friend). Consequently, the perception of a similar other may activate both family concepts and pleasant concepts (which may also activate each other), and therefore, a comparison of the strength of these associations on its own may not be highly informative. Additional methods were thus employed to disentangle the operation of kin-recognition mechanisms from other, conceptually distinct processes. First, participants completed a questionnaire that measured their tendency to make reflexive, intuitive judgments. If human kin recognition is—like many other evolved processes—rooted in psychological mechanisms that respond automatically to heuristic cues, then the automatic activation of kinship cognitions may be especially strong among individuals who, in general, allow themselves to trust their intuitions. Accordingly, individual differences in the tendency to make intuitive judgments were hypothesized to predict similar-family associations more strongly than similar-pleasant associations (Hypothesis 2). Participants were also asked to provide self-report reactions to the target individuals—such as willingness to help the similar and dissimilar target persons—to assess the relationships between implicit associations and explicit prosocial responses. It was hypothesized that similar-family associations would more strongly predict prosocial responses toward the similar target than would similar-pleasant associations (Hypothesis 3). Finally, one additional question was explored in this study: Are implicit kinrecognition responses to attitude similarity sensitive to heritability? Because previous research has revealed effects of attitude heritability in attraction to similar others (Tesser, 1993), attitude heritability was manipulated to examine whether it may affect the tendency to make similar-family (and similar-pleasant) associations. It was hypothesized that similar-family associations would be stronger when perceiving individuals who are similar along more highly heritable attitudes (Hypothesis 4).  35 3.3. Method Forty-five university students (29 women, 16 men) participated in this study. Thirty-two participants were of East Asian background, 7 were of European background, and 6 were of other ethnic backgrounds. (Data from 2 additional students were excluded because they did not complete the computer tasks correctly.) After a practice IAT task, participants completed several questionnaires assessing selected demographic variables and individual differences. One of these questionnaires assessed individual differences in Faith in Intuition (Epstein, Pacini, Denes-Raj, & Heier, 1996; Appendix A). This questionnaire asks participants to indicate their level of agreement with 12 statements that assess the extent to which they trust their hunches, intuitive feelings, and first impressions (e.g., "When it comes to trusting people, I can usually rely on my 'gut feelings'"). Participants then completed a brief attitudes questionnaire (Appendices B and C). This questionnaire presented them with five statements relevant to particular issues or activities (e.g., death penalty for murder). Participants were asked to indicate their own attitudes by rating their level of agreement with each statement. There were two versions of the attitudes questionnaire: Approximately half the participants were presented with high-heritability attitude items, the rest with low-heritability items (taken from Olson et al.,200T). The mean heritability estimates of attitudes in the high- and low-heritability J  conditions were .53 and .02, respectively. Participants were then introduced to two female individuals, Elaine and Carol. They were shown three photos of Elaine and three photos of Carol; these photos were subsequently used as stimuli in the IAT tasks. (All photos were headshots obtained from These heritability estimates were obtainedfromtwin samples living in London, Ontario and Vancouver, British Columbia. 3  36 the Internet. The two women were similar in age and attractiveness, and the pairing between the photos and the names was counterbalanced across participants.) Participants were asked to recall their own responses on the attitudes questionnaire and were asked to "imagine that Elaine gave the same responses as you, and imagine that Carol responded very differently." To further stimulate participants' imagination, they were asked to guess how Elaine might have responded on three additional attitude items. As a result of these procedures, participants acquired visual representations of two individuals—one individual imagined to be attitudinally similar (Elaine), the other individual attitudinally dissimilar (Carol). Participants then completed two IAT tasks on the computer. In these tasks, participants are presented with a specific stimulus (e.g., a word or a photo) and are asked to categorize as quickly as possible each stimulus item into one of two categories by pressing specified keys, with either the left or right index finger, on the computer keyboard. The recorded reactions times can then be used to draw inferences about implicit cognitive associations between different kinds of stimulus items. For one task (similar-family IAT), participants judged whether the stimulus photos depicted Elaine or Carol, and also categorized words (brother, family, kin, kinship, mother, sister; distant, outcast, outsider, stranger, unfamiliar, unknown) as connoting either family or stranger. (In pretesting, 20 additional participants rated the pleasantness of these stimulus words on a 10-point scale with endpoints labeled very unpleasant and very pleasant. The mean pleasantness rating was 8.30 for the six family words and 3.96 for the six stranger words.) There were two critical blocks, consisting of 40 trials each. In one block, the response categories Elaine and family shared one response key on the keyboard, whereas Carol and stranger shared another response key. If the attitudinally similar other (Elaine) is associated with family concepts, then this particular response-  37 key arrangement is psychologically consistent, which may result in relatively short reaction times. In the other critical block of trials, Elaine and stranger shared one response key, whereas Carol and family shared another response key. If the attitudinally similar other (Elaine) is associated with family concepts, then this particular responsekey arrangement is psychologically conflicting, which may result in relatively long reaction times. The greater the implicit cognitive association between Elaine and family, the greater is the divergence in average reaction times across the two critical blocks. Therefore, the difference in average reaction times across the two blocks of trials serves as an indicator of implicit cognitive association (referred to as the IAT effect). Larger IAT effects in this task indicated stronger cognitive activation of family concepts in response to the perception of an attitudinally similar other. Participants also completed another IAT task {similar-pleasant IAT) that assessed implicit associations between Elaine and pleasant. The procedure for the pleasant IAT task was identical to that of the family IAT task, except that participants judged a different set of stimulus words (friend, joy, kind, laughter, peace, trust; dirty, failure, hate, hostile, stupid, terrible). These words are irrelevant to kinship relations, but they are all evaluatively positive or negative in a broader sense. (In pretesting, the mean pleasantness rating was 9.20 for the six pleasant words and 2.42 for the six unpleasant words. Thus, these words were even more extreme in positive-negative valence than the stimulus words used in the similar-family IAT, described above.) Participants categorized these words as either pleasant or unpleasant. Larger IAT effects on this task indicated stronger cognitive activation of pleasant concepts in response to the perception of an attitudinally similar other. Participants completed both IAT tasks; the order was counterbalanced. After the IAT tasks, participants completed additional questionnaires. One questionnaire  38 reintroduced the attitude items and asked participants to indicate how important each attitude was to them and how strongly they held each attitude. (Consistent with previous research, Tesser, 1993, high-heritability attitude items were considered more important and were held more strongly.) Another questionnaire asked three questions about Elaine and Carol: (1) to what extent participants could see things from Elaine's and Carol's perspective; (2) to what extent participants would be willing to assist Elaine and Carol should they require help; and (3) to what extent they thought they shared genes with Elaine and Carol (this third question was exploratory and was prefaced by a description of the genetic bases of attitudes; Appendix D).  3.4. Results To calculate implicit associations linking the target individuals to semantic concepts, the recommended scoring algorithm was applied to the reaction-time data, which reduces the biasing effects of unusual reaction times (for computational details, see Greenwald, Nosek, & Banaji, 2003). The resulting values of IAT effects are akin to standardized effect sizes, and more positive values on the two IAT indices indicate stronger implicit cognitive associations linking the attitudinally similar other (Elaine) to family and to pleasant concepts. Consistent with Hypothesis 1, the results revealed that the attitudinally similar target person was—relative to the dissimilar person—implicitly associated with family concepts (M= .24, p < .001). As expected, the similar target person was also associated with pleasant concepts (M= .23, p < .001). The two IAT effects did not differ in strength (p > .50), nor were these two indices substantially correlated (r = .23, p ^ .13). Furthermore, analyses revealed that heritability of attitudes had no effect on either IAT  39 effect (bothps > .75), indicating no support for Hypothesis 4. Therefore, the results described below are collapsed across the two heritability conditions. The unique relation between attitude similarity and family concepts was clarified by additional analyses examining the moderating effects of a conceptually relevant individual-difference variable. Faith in Intuition was positively correlated with similarfamily associations (r = .33, p = .03), but not with similar-pleasant associations (r = .05, p = .72). However, the difference between these correlations was not statistically significant (p = .13); thus, Hypothesis 2 was partially supported. Regression lines associated with these two relations are presented in Figure 3.1. Participants who reported that they tend to rely on first impressions and gut feelings to navigate their social world showed an especially strong tendency to make similar-family associations. Those who placed little trust in their intuitions (and so are more likely to use rational thought to overrule automatically activated gut feelings) did not show this tendency. No such moderating effect occurred on the similar-pleasant IAT effects.  Faith in Intuition  Figure 3.1. Regression lines indicating predictive effects of Faith in Intuition on implicit associations linking similar other to family and to pleasant.  40 Participants had also answered three additional questions concerning ease of perspective-taking, willingness to help, and estimation of shared genes. Results showed that Elaine (the similar other) was given higher ratings than Carol (the dissimilar other) for all three questions (all ps < .001). Further analyses examined whether these judgmental discriminations between the similar and dissimilar target persons were correlated with implicit associations. To do so, a difference score was calculated for each question by subtracting the rating of Carol from the rating of Elaine, so that higher values indicate judgmental discrimination in favor of the attitudinally similar target person. Discrimination on the perspective-taking judgment was positively predicted by similarfamily associations (r - .32, p = .03), but not similar-pleasant associations (r = -.16, p = .29); these correlations differed significantly (p = .009). Discrimination in willingness to help was predicted by similar-family associations (r = .33,p = .03), but not similarpleasant associations (r = 22, p = .15); however, these correlations did not differ significantly (p > .50). Therefore, Hypothesis 3 was partially supported. Discrimination in estimates of shared genes was correlated only weakly with both similar-family associations (r = .12, p = .42) and similar-pleasant associations (r = .25, p = .09). There was one additional finding. The number of participants' younger siblings was weakly correlated with similar-family associations (r = .27, p = .07), but not similarpleasant associations (r = -.03,p = .86). Neither IAT effect was correlated with the number of older siblings. Although speculative at this point, it's possible that the presence of siblings influences the reactivity of kin-recognition mechanisms.  3.5. Discussion  The hypotheses were partially supported. Consistent with Hypothesis 1, results showed that the perception of an attitudinally similar other automatically activated  41 kinship concepts. As expected, participants also implicitly associated the similar other with pleasant concepts in general. Faith in Intuition predicted similar-family associations more strongly than similar-pleasant associations, but the correlations did not differ significantly; thus, Hypothesis 2 was partially supported. Results also revealed that similar-family associations (but not similar-pleasant associations) predicted ease of taking the similar person's perspective and willingness to help the similar person. The predictive effects of the two IAT effects differed significantly for the former but not the latter; thus, Hypothesis 3 was partially supported. There was no evidence that similarfamily or similar-pleasant associations were affected by heritability of attitudes; thus, there was no support for Hypothesis 4. Although the findings are generally consistent with the broader hypothesis that attitude similarity may serve as a kinship cue, several methodological limitations temper the conclusions that can be drawn. These limitations also highlight the reasons why it may have been difficult to obtain strong support for the hypotheses. One limitation was the use of the categories "family" and "stranger" in the family IAT task. It's possible that people may apply the term "family" flexibly; thus, this conceptual category may include other kinds of close relationships (e.g., spouse, friend) that are not characterized by genetic relatedness. Therefore, although the presence of similar-family associations may imply that participants were associating the similar other specifically with the concept of genetic kinship, it may also imply that participants were associating the similar other with a broader class of relationship concepts comprising kin, spouse, and close friends. This is likely, given that there are high degrees of attitude similarity not only between genetic kin, but also between spouses and friends (Rushton & Bons, 2005). In order to test this alternative explanation, studies with.more specific IAT tasks (e.g., tasks that can disentangle similar-kin associations from similar-friend  42 associations) need to be conducted. What would be the implications if the concept "family" includes nongenetic relationships? Although this would not necessarily contradict the operation of kin-recognition mechanisms, it would imply that human kinrecognition mechanisms may not be specific to genetic relationships, possibly because evolved kin-recognition mechanisms have been co-opted by psychological mechanisms governing other close relationships or because the conceptual category "family" is highly plastic, readily extending to nongenetic relationships. Another weakness of the study is that although there was some evidence for the distinction between similar-family and similar-pleasant associations, not all of the tests of the differences (between correlations) were statistically significant. In some cases, this may reflect the sample size; in other cases, this may indicate that similar-family associations are not psychologically separable from similar-pleasant associations. There may be good reasons for this. Family concepts and pleasant concepts are not semantically independent; rather, family concepts represent a subset of a broader category of pleasant concepts. Given this overlap, it may have been difficult to observe the effects specified by Hypotheses 2 and 3. Thus, it's particularly significant that any distinction was observed between similar-family and similar-pleasant associations. These considerations suggest that methodologies that do not rely on measurements of semantic concepts (e.g., physiological measures of empathy) may usefully complement the methods used in the present study. Finally, the role of attitude heritability in kin-recognition processes remains unclear. Although previous research suggests that heritability of attitudes may be relevant to person perception (Tesser, 1993), the results of the present study revealed no effects of heritability on the implicit associations. This may be due to a number of reasons. First, because the IAT tasks are cognitively demanding, it's possible that  43 participants simply forgot about the specific attitude items (and only remembered that one target was similar and the other was dissimilar). Second, because heritability estimates may vary depending on the study sample, it's possible that the heritability information (taken from Olson et al., 2001) was not diagnostic for the participants in the present study. Finally, it's possible that heuristic kin-recognition responses to attitude similarity simply are not sensitive to heritability information. The take-home points are the following. A n attitudinally similar other automatically activated both family concepts and pleasant concepts, but the similarfamily and similar-pleasant associations were separable to some extent: The similarfamily associations were more likely to predict perspective-taking with and prosoeial inclinations toward the similar other. However, more research is needed to clarify the link between attitude similarity and kinship cognitions. Future research might also investigate more rigorously the impact of early family environment (e.g., number of siblings) on the tendency to respond to heuristic kinship cues.  3.6. Broader Implications of Kin-Recognition Mechanisms The possibility that kin recognition may occur even in interactions between strangers has several implications for understanding the positive consequences of perceived similarity. Social psychological research has documented many effects of perceived similarity—including effects on liking, perspective taking, empathy, and helping behavior (e.g., Batson et a l , 1981; Byrne et al., 1971; Krebs, 1975). There are surely multiple psychological processes that account for these effects of similarity. It's possible that one of these processes is rooted in the psychology of kin recognition. Indeed, several widely documented phenomena in social psychology may have kinrecognition processes at their roots.  44 3.6.1. Empathy and altruism. The empathy-altruism hypothesis suggests that empathy facilitates helping by activating the goal to improve the welfare of the needy individual (Batson, 1990). Evidence seems to support this hypothesis: In general, a higher degree of empathy toward another person promotes helping behavior (e.g., Batson et al., 1981). However, much debate has surrounded whether empathy-induced helping is genuinely altruistic or whether it involves the activation of egoistic mood-management goals (e.g., Batson & Shaw, 1991; Cialdini et al., 1987). A possible resolution may involve conceptualizing the empathy-altruism effect as a component of nepotism. It appears that empathy-induced helping often occurs reflexively without much deliberation, so it's not clear whether any explicit goals are actually activated at all (Krebs, 1987; Schaller, 2003). Moreover, the theoretical implications of kin-recognition mechanisms offer grounds for situating the empathy-altruism effect within the framework of nepotism: The perception of kinship cues may automatically activate kinship cognitions and emotions (including empathy), which may reflexively motivate prosocial responses. 3.6.2. Interpersonal processes. Helping behavior has also been investigated in terms of types of relationships, specifically, communal and exchange relationships (Clark, 1984; Clark & Mills, 1979). In communal relationships—typified by family relations and close friendships—benefits are given in response to need; in exchange relationships, benefits are given in exchange for previously received benefit. These two types of relationships parallel qualitatively distinct biological origins of helping—kin altruism and reciprocal altruism (Hamilton, 1964; Trivers, 1971)—as well as other classifications of core relationships (Bugental, 2000; Fiske, 1992; Kenrick, L i , & Butner, 2003). It seems likely that the psychology of kin recognition partly underlies communal relationships; i f so, this may add novel insight to communal and exchange relationships. For instance, the presence of kinship cues (e.g., similarity) may facilitate communal relationships. There  45 is some evidence that is consistent with this speculation (Clark & Mills, 1979), but future research might test this hypothesis more directly. In contexts that demand cooperation between individuals (i.e., exchange relationships), specific psychological responses appear to be activated by violations of reciprocity norms. For instance, people are quick to notice violations of social exchange in Wason card tasks and to punish defectors in Prisoner's Dilemma games (Cosmides & Tooby, 1992). There is evidence that individuals portrayed as defectors are remembered better (Oda, 1997). There is also intriguing evidence suggesting that real defectors can be perceptually distinguished from real cooperators (Yamagishi, Tanida, Mashima, Shimoma, & Kanazawa, 2003). Moreover, the desire to punish noncooperative ingroup members may be stronger than the desire to punish noncooperative outgroup members. This is because punishment is part of the psychology of reciprocal altruism, which is designed primarily for within-group interactions (Shinada, Yamagishi, & Ohmura, 2004). Such propensities for cheater detection and punishment of defectors are a part of the broader set of evolved mechanisms pertaining to reciprocal altruism (Axelrod & Hamilton, 1981; Trivers, 1971). However, such violations of reciprocity norms are less problematic—in terms of reproductive fitness—within kin relationships. The essence of nepotism is, after all, unconditional giving. Therefore, a possible implication is that the heuristic perception of kinship may temper cheater-detection responses and the desire to punish defectors. Research on nonhuman primates offers some evidence for this hypothesis. Like many other primate species, chimpanzees are sensitive to inequity in benefits received between them and other chimpanzees. In one study, chimpanzees that were offered a low-value reward after observing a partner chimpanzee receiving a high-value reward displayed displeasure by refusing the reward. But such displeasure was observed only when their  46 partner was relatively unfamiliar; the chimpanzees tolerated the inequity if their partner was highly familiar (Brosnan, Schiff, & de Waal, 2005). Future research might test this idea more directly among humans. One hypothesis is that the heuristic perception of kinship may reduce the tendency to notice cheaters and to punish defectors. And such an effect may be mediated by the automatic activation of kinship cognitions and emotions. The fact that punishment is more likely toward noncooperative ingroup members than outgroup members (Shinada et al., 2004) suggests an interesting test: The tendency to notice and react negatively to noncooperators may be stronger in the presence of cues for ingroup membership, but weaker in the presence of cues for kinship. 3.6.3. Morality. Finally, kin recognition—and the psychology of kinship more broadly—may have implications for the psychology of morality. There is evidence that moral judgments may occur automatically; for instance, people tend to judge incestuous acts as morally wrong with little rational thought (Haidt, 2001). As previously mentioned, the tendency to judge incest as morally wrong is stronger among individuals who have lived with opposite-sex siblings for longer periods, suggesting that this particular moral judgment may be closely tied to the mechanisms involved in the perception of kin (Lieberman, Tooby, & Cosmides, 2003). Other theorists have also drawn links between evolved psychological mechanisms and moral norms. For instance, Krebs and Janicki (2004) argue that morality is a product of a social species whose members needed to get along with one another. More specifically, different categories of moral norms may have emerged for different relationship domains, including obedience norms (for authoritybased relationships), reciprocity norms (for cooperative relationships), and altruistic norms (for kin relationships). Specific examples of these moral norms can be found in religious prescriptions such as "honor your parents," "do unto others as you would have them do to you" and "love your neighbors as you love yourself."  47 The possible link between the psychology of kinship and altruistic moral norms (Krebs & Janicki, 2004) implies several hypotheses concerning people's moral judgments about other people. For instance, altruistic moral norms evolved in part to regulate kin relationships, one hypothesis is that such norms may be especially salient and compelling when people are making moral decisions involving individuals who are heuristically perceived as kin. By the same token, appeals for people to be more altruistic often involve attempts to directly activate kin-based altruistic norms (e.g., we should help others because we're part of a "human family").  3.7. Conclusion The theoretical considerations of kin-recognition mechanisms generated several hypotheses concerning how individuals may perceptually discriminate others and what thoughts, feelings, and behaviors may be activated by the heuristic perception of kinship. The study described in this chapter found some evidence suggesting that attitude similarity may serve as a heuristic cue for kinship, which may promote prosoeial tendencies even between strangers. Clearly, more research is needed to clarify issues such as whether there is an evolved tendency to respond specifically to attitude similarity as a kinship cue and how people may represent the concept of kinship. But the present findings are important, as they suggest that kin-recognition mechanisms may operate in a wide range of circumstances. In the next chapter, I explore a different adaptive problem that may have led to the evolution of another set of cue-recognition mechanisms.  3.8. References Axelrod, R., & Hamilton, W. D. (1981). The evolution of cooperation. Science, 211, 1390-1396.  48 Batson, C. D. (1990). How social an animal? The human capacity for caring. American Psychologist, 45, 336-346. Batson, C. D., Duncan, B . D., Ackerman, P., Buckley, T., & Birch, K . (1981). Is empathic emotion a source of altruistic motivation? Journal of Personality and Social Psychology, 40, 290-302. Batson, C. D., & Shaw, L. L . (1991). Evidence for altruism: Toward a pluralism of prosoeial motives. Psychological Inquiry, 2, 107-122. Brosnan, S. F., Schiff, H. C , & de Waal, F. B. M . (2005). Tolerance for inequity may increase with social closeness in chimpanzees. Proceedings of the Royal Society of London B, 272, 253-258. Bugental, D. B . (2000). Acquisition of the algorithms of social life: A domain-based approach. Psychological Bulletin, 126, 187-219. Byrne, D., Gouaux, C., Griffitt, W., Lamberth, J., Murakawa, N . , Prasad, M . B., et al. (1971). The ubiquitous relationship; Attitude similarity and attraction: A crosscultural study. Human Relations, 24, 201-207. Chen, F., & Kenrick, D. T. (2002). Repulsion or attraction? Group membership and assumed attitude similarity. Journal of Personality and Social Psychology, 83, 111-125. Cialdini, R. B., Schaller, M . , Houlihan, D., Arps, K., Fultz, J., & Beaman, A . L . (1987). Empathy-based helping: Is it selflessly or selfishly motivated? Journal of Personality and Social Psychology, 52, 749-758. Clark, M . S. (1984). Record keeping in two types of relationships. Journal of Personality and Social Psychology, 47, 549-557. Clark, M . S., & Mills, J. (1979). Interpersonal attraction in exchange and communal relationships. Journal of Personality and Social Psychology, 37, 12-24.  Cosmides, L., & Tooby, J. (1992). Cognitive adaptations for social exchange. In J. H . Barkow, L. Cosmides, & J. Tooby (Eds.), The adapted mind: Evolutionary psychology and the generation of culture (pp. 163-228). New York: Oxford University Press. DeBruine, L. M . (2002). Facial resemblance enhances trust. Proceedings of the Royal Society of London B, 269, 1307-1312. Epstein, S., Pacini, R., Denes-Raj, V., & Heier, H. (1996). Individual differences in intuitive-experiential and analytical-rational thinking styles. Journal of Personality and Social Psychology, 71, 390-405. Fiske, A. P. (1992). The four elementary forms of sociality: Framework for a unified theory of social relations. Psychological Review, 99, 689-723. Greenwald, A . G., McGhee, D. E., & Schwartz, J. L . K . (1998). Measuring individual differences in implicit cognition: The implicit association test. Journal of Personality and Social Psychology, 74, 1464-1480. Greenwald, A. G., Nosek, B. A., & Banaji, M . (2003). Understanding and using the implicit association test: I. A n improved scoring algorithm. Journal of Personality and Social Psychology, 85, 197-216. Haidt, J. (2001). The emotional dog and its rational tail: A social intuitionist approach to moral judgment. Psychological Review, 108, 814-834. Hamilton, W. D. (1964). The genetical evolution of social behaviour. Journal of . Theoretical Biology, 7, 1-52. Kenrick, D. T., L i , N . P., & Butner, J. (2003). Dynamical evolutionary psychology: Individual decision rules and emergent social norms. Psychological Review, 110, 3-28.  50 Krebs, D. (1975). Empathy and altruism. Journal of Personality and Social Psychology, 32, 1134-1146. Krebs, D. (1987). The challenge of altruism in biology and psychology. In C. Crawford, M . Smith, & D. Krebs (Eds.), Sociobiology and psychology: Ideas, issues, and applications (pp. 81-118). Hillsdale, NJ: Erlbaum. Krebs, D., & Janicki, M . (2004). Biological foundations of moral norms. In M . Schaller & C. S. Crandall (Eds.), The psychological foundations of culture (pp. 125-148). Mahwah, NJ: Erlbaum. Lieberman, D., Tooby, J., & Cosmides, L. (2003). Does morality have a biological basis? A n empirical test of the factors governing moral sentiments regarding incest. Proceedings of the Royal Society of London B, 270, 819-826. Oates, K., & Wilson, M . (2002). Nominal kinship cues facilitate altruism. Proceedings of the Royal Society of London B, 269, 105-109. Oda, R. (1997). Biased face recognition in the Prisoner's Dilemma game. Evolution and Human Behavior, 18, 309-315. Olson, J. M . , Vernon, P. A., Harris, J. A., & Jang, K. L . (2001). The heritability of attitudes: A study of twins. Journal of Personality and Social Psychology, 80, 845-860. Rushton, J. P., & Bons, T. A . (2005). Mate choice and friendships in twins: Evidence for genetic similarity. Psychological Science, 16, 555-559. Schaller, M . (2003). Ancestral environments and motivated social perception: Goal-like blasts from the evolutionary past. In S. J. Spencer, S. Fein, M . P. Zanna, & J. M . Olson (Eds.), Motivated social perception: The Ontario Symposium (pp. 215-231). Mahwah, NJ: Erlbaum.  51 Shinada, M . , Yamagishi, T., & Ohmura, Y. (2004). False friends are worse than bitter enemies: "Altruistic" punishment of in-group members. Evolution and Human Behavior, 25, 379-393. Tesser, A. (1993). The importance of heritability in psychological research: The case of attitudes. Psychological Review, 100, 129-142. Trivers, R. L . (1971). The evolution of reciprocal altruism. Quarterly Review of Biology, 46, 35-57. Yamagishi, T., Tanida, S., Mashima, R., Shimoma, E., & Kanazawa, S. (2003). You can judge a book by its cover: Evidence that cheaters may look different from cooperators. Evolution and Human Behavior, 24, 290-301.  52 Chapter 4. Parasite-Recognition Mechanisms  4.1. Introduction Many cue-recognition mechanisms—such as those underlying nepotism—identify individuals to approach for beneficial interactions. But many other cue-recognition mechanisms identify potentially harmful individuals to avoid. Several such mechanisms have been investigated in humans, many of which have been invoked to explain the tendency for people to stigmatize specific kinds of individuals (Cottrell & Neuberg, 2005; Kurzban & Leary, 2001; Stangor & Crandall, 2000). For instance, it has been found that humans are quick to stigmatize nonreciprocators (e.g., thieves, people with disabilities), individuals with treacherous characteristics (e.g., cheaters, traitors), individuals who threaten group integrity (e.g., people with radically different values), and individuals belonging to outgroups (e.g., ethnic outgroup members). O f course, problems associated with group living are not limited to the social domain. There is a much more fundamental problem associated with living in proximity to conspecifics: parasites.  4.2. Adaptive Context of Parasite Recognition Parasites are small predators—viruses, bacteria, worms—that exploit another organism's resources in order to reproduce, often causing serious damage to the host (Ewald, 2000). Because parasites are often communicable, they are particularly harmful for group-living species, especially as populations become denser. The relationship between population density and parasite prevalence isn't a recent phenomenon restricted to humans living in unsanitary urban areas; rather, it appears to be a fundamental aspect of ecology observed across species (e.g., Nunn, Altizer, Jones, & Sechrest, 2003). Of course, unprecedented levels of population density do exacerbate the problem  53 significantly. For urban-dwelling humans, the destruction caused by parasites has been staggering. Most notably, the "Black Death" in the 1300s killed 20 million people, and the "Spanish Flu" in the 1900s killed over 25 million people. And because affected groups of humans quickly acquire heritable immunity to highly potent parasites (such that they may harbor the parasites without dying), contact between previously divided populations has been disastrous for many groups, such as the indigenous peoples of the American continents (Diamond, 1997). The adaptive problems associated with parasites are straightforward: Organisms infected with parasites are less likely to survive and reproduce than those not infected. In response to such selection pressure, host organisms have evolved several defenses, such as physical barriers and the immune system. Such features that prevented infection would have been selected, becoming species-wide adaptations. But the problem of parasites is ongoing, because parasites evolve—at much faster rates than their hosts—the ability to penetrate the defenses. Given the sustained selection pressure imposed by parasites, animals likely evolved several ways of defending themselves. There is one class of defense mechanisms that has received relatively little attention: behavioral avoidance. Because parasites are most likely to be transmitted between biologically similar organisms living in proximity, a general tendency to avoid conspecifics is one way to prevent infection. But given the benefits associated with sociality—not to mention the difficulty of reproducing without physical contact—a better solution is to avoid only those conspecifics that are actually carrying parasites. Research has found that many nonhuman animals engage in behavioral avoidance of conspecifics that show signs of illness (Goodall, 1986; Kavaliers & Colwell, 1995; Loehle, 1995). Humans likely possess similar behavioral defenses; indeed, parasite avoidance has been described as a  54 major contributor to stigmatization of specific kinds of individuals (Kurzban & Leary, 2001). People's tendency to avoid infected individuals can be found in historical evidence as well. Physical isolation has been a common treatment of diseased individuals throughout history (Conrad & Wujastyk, 2000). In fact, the word "quarantine" originated in the Black Death period of the fourteenth century during which travelers from infected places were isolated for 40 days (Cartwright & Biddiss, 2000). Of course, the tendency to avoid infected conspecifics requires the ability to perceptually recognize which conspecifics are infected in the first place. Many parasites are microscopic and are not directly perceptible. But because their activities leave characteristic markers on their hosts, animals can use these markers as signals for the presence of parasites (Kurzban & Leary, 2001).  4.3. Parasite Cues So what cues do animals use to recognize parasites? Some animals may use olfactory cues: Studies have revealed that female mice prefer the odor of nonparasitized males to that of parasitized ones (Kavaliers & Colwell, 1995). Similar odor-based discrimination has been observed among beetles (Worden, Parker, & Pappas, 2000). Although little research has investigated olfactory parasite recognition among humans, there is some suggestive evidence. Studies have found that women prefer the scent of symmetrical men when the probability of conception is high (Gangestad & Thornhill, 1998; Thornhill & Gangestad, 1999). As discussed below, symmetry—a contributor to attractiveness—may be associated with the absence of parasites or with parasite resistance. Parasites also leave visible markers by disrupting species-typical appearance— markers such as skin lesions, discolorations, and asymmetries (Kurzban & Leary, 2001).  55 Given the correlation between visible markers and parasites, animals may quickly learn to associate anomalous appearances in conspecifics with the presence of parasites. The perception of parasite cues may then automatically activate mechanisms that motivate behavioral avoidance. Animals do seem to respond to visible anomalies. For instance, Goodall (1986) observed chimpanzees maintaining physical distance from other chimpanzees that, as the result of polio, had lost the use of some of their limbs. Humans also exhibit strong reactions to visible markers (consider the universally negative reactions to individuals with leprosy). There is empirical evidence demonstrating that people avoid individuals displaying visible anomalies such as facial discoloration (e.g., Houston & Bull, 1994). Furthermore, the social psychological literature on stigma reveals the importance of visible cues: Theory and research has consistently identified visibility as a key factor in stigmatization (Goffman, 1963; Jones et al., 1984; Katz, 1981). Of course, visibility per se isn't what matters; visibility is a key factor insofar as it refers to deviation from some normative standard ("normal-looking" features, no matter how • visible, tend not to be stigmatized).  4.4. Functional Cognitions and Emotions What functional cognitions are activated by the perception of parasite-connoting cues? Among humans, functional cognitions may include appraisals about contagion and contamination (Rozin, Millman, & Nemeroff, 1986; Woody & Teachman, 2000). These appraisals need not be sophisticated; the relatively recent emergence of biological germ theory reveals that people do not spontaneously understand the complex interactions between parasites and disease. Nevertheless, the perception of parasite cues may activate some rudimentary—but subjectively compelling—cognitions pertaining to the transmission of harmful substances. People seem to belief that "things that once have  56 been in contact with each other may influence each other through transfer of some of their properties via an 'essence'" (Rozin et al., 1986, p. 703). Research in developmental psychology has found that the notion of contagion is something that children learn very quickly (Ralish, 1996; Solomon & Cassimatis, 1999). Among adults, the desire to avoid diseased others is correlated with the perceived contagiousness of the disease (Bishop, 1991; Crandall & Moriarty, 1995). And historical evidence indicates that people have long possessed an understanding of disease as something that can be communicated interpersonally, though their understanding may have been rudimentary (Conrad & Wujastyk, 2000). Functional cognitions may also comprise activation of semantic concepts associated with illness. These concepts may take the form of stereotypic beliefs about. potentially infected individuals. Perceptions of people infected with parasites—or people displaying parasite cues—may activate stereotypic beliefs such as unhealthy and unclean. At an implicit level, the perception of individuals displaying parasite cues may automatically activate concepts related to contagion and disease. Typically, these semantic concepts are evaluatively negative and thus may motivate behavioral avoidance. What functional emotions are activated by the perception of parasite-connoting cues? It has been suggested that disgust evolved as an emotional response to disease and contamination (Curtis, Aunger, & Rabie, 2004; Woody & Teachman, 2000). Indeed, things that transmit parasites (e.g., feces, flesh wounds, rotting food) are reliable elicitors of disgust across cultures, and disgust consistently motivates physical avoidance (Curtis & Biran, 2001). Evidence for the role of disgust in parasite-avoidance processes can be found in the clinical psychological literature. Individual differences in disgust sensitivity are associated with phobias of spiders and small animals (Mulkens, de Jong, & Merckelback, 1996; Woody, McLean, & Klassen, 2005). Also, in both clinical and  57 nonclinical samples, obsessive-compulsive tendencies are associated with disgust sensitivity—especially among individuals with washing compulsions (Mancini, Gragnani, & D'Olimpio, 2001; Woody & Tolin, 2002). Individuals with obsessive-compulsive disorder also show greater activation of brain areas associated with disgust—the amygdala and the anterior insula—when presented with disgust-inducing stimuli (Phillips et al., 1998; Shapira et al., 2003; Stark et al., 2003). The pervasive judgments of physical attractiveness may also be relevant to parasite recognition. Among infected individuals, bodies and faces may be marked by cues (discolorations, deformities) that clearly stand out as unattractive. But even among relatively healthy individuals, some individuals are simply judged to be more attractive than others—and this too may be relevant to parasite recognition. Research on subjective attractiveness of faces has identified two related features that contribute to attractiveness: symmetry and "averageness" (Grammer & Thornhill, 1994; Langlois & Roggman, 1990). Averageness doesn't imply mediocre attractiveness; it implies average sizes of and distances between facial features ("average" faces can be created by digitally morphing several faces together—and the morphs tend to be highly attractive). There are, however, disagreements about what exactly subjective attractiveness represents. Several researchers have found correlations between subjective attractiveness of faces and objective indicators of health (Henderson & Anglin, 2003; Hume & Montgomeri, 2001; Shackelford & Larsen, 1997, 1999). Accordingly, one view is that attractiveness accurately signals mate quality (e.g., fertility, parasite resistance), and preferences for attractiveness evolved because such preferences conferred reproductive advantage. This view can be summed up as "find healthy mate." However, other researchers have failed to find relationships between attractiveness and health. These researchers suggest instead that we naturally respond  58 aversively to faces characterized by actual ill health (asymmetrical and atypical faces), and as a byproduct, faces that lack anomaly (symmetrical and average faces) are perceived to be more attractive (Kalick, Zebrowitz, Langlois, & Johnson, 1998; Rhodes et al., 2001). This view can be summed up as "avoid diseased people." Consistent with this view, there is evidence that perceptual mechanisms that detect actual diseaseconnoting anomalies may respond overinclusively to unattractive—but not necessarily unhealthy—faces as well (Zebrowitz, Fellous, Mignault, & Andreoletti, 2003). It seems likely that both "find healthy mate" and "avoid diseased people" processes operate. People may be drawn to highly attractive individuals as part of a mating strategy; people may also avoid unattractive individuals because of the falsepositive bias of parasite-recognition mechanisms. A s this discussion suggests, parasite recognition may take on added significance in the context of mating. This issue is explored further in chapter 7.  4.5. Recognition Errors Parasite recognition is far from perfect because the correlation between visible markers and the presence of parasites is far from perfect. Consequently, false-positive errors (perceiving a healthy individual to be a parasite carrier) and false-negative errors (perceiving a parasite carrier to be healthy) are an inevitable part of cue-based inferences regarding parasite presence. Again, the functional consequences of the two types of errors are not symmetrical; in general, false-negative errors are likely to incur heavier costs than false-positive errors (one false-negative error may be lethal). As a result, parasite-recognition mechanisms may be biased toward false-positive errors (Kurzban & Leary, 2001). In other words, parasite-recognition mechanisms may be sensitive to a wide range of physical or behavioral features that are perceived simply to deviate from  59 some normative standard. Moreover, the frequency of false-positive errors may increase in the presence of novel stimuli that resemble parasite cues or that simply appear unusual. The success of many gruesome-looking costumes and makeovers (e.g., in movies, for Halloween) depends on such recognition errors.  4.6. Functional Flexibility Though automatic, responses to the perception of parasites may be influenced by additional variables. The extent to which specific anomalous features are associated with parasites may depend on learning experiences—and as result, parasite cues may differ in different contexts. For example, physical markers that are associated with a disease that happens to be prevalent in a particular context may arouse especially strong responses among people living in that context. More broadly, the tendency to perceive unusual features as parasite cues requires the acquisition of some normative standard that defines "normal" appearance, and this standard may be influenced by local context. Developmental experiences may also adjust the reactivity of individuals' parasiterecognition mechanisms. For instance, individuals living in ecological contexts characterized by high parasite prevalence may have heightened reactivity to parasite cues. This may explain why physical attractiveness—a cue that may signal parasite resistance or the absence of parasites—is more highly valued in locations with a high parasite load (Gangestad & Buss, 1993). On a day-to-day basis, parasite-recognition mechanisms may be sensitive to background variables concerning the degree to which one is susceptible to parasites. This is because engaging in metabolically costly avoidant behaviors is more likely to pay off if there is a greater baseline likelihood of being infected by parasites. Some of these background variables may be provided by individual differences in vulnerability to  60 parasites, or even perceived vulnerability to parasites. Thus, a greater chronic wariness of parasites may be associated with stronger responses to individuals displaying parasite cues. Other background variables may be internal and temporary: "If some physiological state is indicative of enhanced parasite susceptibility, then an organism in that state should take extra measures to avoid contact with pathogens" (Loehle, 1995, p. 329). Indeed, sick animals tend to behave in ways that reduce the likelihood of contracting additional diseases (Hart, 1990). Finally, any contextual factor that makes one feel temporarily more vulnerable to the transmission of disease may facilitate more negative reactions toward individuals displaying parasite cues. For instance, increased salience of diseases (e.g., as a result of media's focus on anthrax, SARS, avian flu) may temporarily heighten parasite-recognition responses, possibly resulting in greater avoidance of individuals with diseases and individuals who simply appear unusual.  4.7. Heuristic and Reflective Processes In addition to responding automatically to heuristic cues, people are also capable of reflective thoughts about disease. Thus, knowledge that someone has an infectious disease (e.g., HIV) may also activate functional psychological responses that motivate avoidant behavior, especially if that knowledge is coupled with the perception of heuristic cues. The situation becomes more complicated when the heuristic and reflective processes yield divergent inferences. What happens when we observe someone who we know is healthy but happens to display apparent parasite cues? Given the automaticity of heuristic mechanisms—due, in part, to their deeper evolutionary history—the perception of parasite cues may automatically activate functional cognitions and emotions, a process that is largely inaccessible to conscious control.  61 More broadly, people's responses to stigmatized individuals have been described as comprising automatic and controlled processes (Devine, 1989; Pryor, Reeder, Yeadon, & Hesson-Mclnnis, 2004). A typical observation is that perceivers' automatic responses to stigmatized individuals tend to be negative, but that perceivers may attempt to exert control over their behavior to appear nonprejudiced. Several distinct processes likely underlie the automatic negative responses; among them may be parasite-recognition mechanisms.  4.8. Conclusion The review of theory and research on parasite-recognition mechanisms suggests that, in addition to responding to actually infected individuals, these mechanisms may also respond to individuals displaying apparent parasite cues. The perception of these cues may automatically activate functional cognitions and emotions that motivate behavioral avoidance. There are several targets of stigma in contemporary contexts (e.g., people with amputated limbs, burn scars) whose unusual appearance might serve as heuristic parasite cues. In the next chapter, I describe a study that tested the hypothesis that physical disabilities may serve as a heuristic cue for parasites.  4.9. References Bishop, G. D. (1991). Lay disease representations and responses to victims of disease. Basic and Applied Social Psychology, 12, 115-132. Cartwright, F. F., & Biddiss, M . (2000). Disease and history. Stroud, United Kingdom: Sutton. Conrad, L. I., & Wujastyk, D. (2000). Contagion: Perspectives from pre-modern societies. Burlington, V T : Ashgate.  Cottrell, C. A., & Neuberg, S. L . (2005). Different emotional reactions to different groups: A sociofunctional threat-based approach to "prejudice." Journal of Personality and Social Psychology, 88, 770-789. Crandall, C. S., & Moriarty, D. (1995). Physical illness stigma and social rejection. British Journal of Social Psychology, 34, 67-83. Curtis, V., Aunger, R., & Rabie, T. (2004). Evidence that disgust evolved to protect from risk of disease. Proceedings of the Royal Society of London B, 271, S131-S133. Curtis, V., & Biran, A. (2001). Dirt, disgust, and disease. Perspectives in Biology and Medicine, 44, 17-31. Devine, P. G. (1989). Stereotypes and prejudice: Their automatic and controlled components. Journal of Personality and Social Psychology, 56, 5-18. Diamond, J. (1997). Guns, germs, and steel: The fates of human societies. New York: Norton. Ewald, P. W. (2000). Plague time: How stealth infections cause cancers, heart disease, and other deadly ailments. New York: The Free Press. Gangestad, S. W., & Buss, D. M . (1993). Pathogen prevalence and human mate preferences. Ethology and Sociobiology, 14, 89-96. Gangestad, S. W., & Thornhill, R. (1998). Menstrual cycle variation in women's preferences for the scent of symmetrical men. Proceedings of the Royal Society of London B, 265, 927-933. Goffman, E. (1963). Stigma: Notes on the management of spoiled identity. Englewood Cliffs, NJ: Prentice-Hall. Goodall, J. (1986). Social rejection, exclusion, and shunning among the Gombe chimpanzees. Ethology and Sociobiology, 7, 227-236.  Grammer, K., & Thornhill, R. (1994). Human (Homo sapiens) facial attractiveness and sexual selection: The role of symmetry and averageness. Journal of Comparative Psychology, 108, 233-242. Hart, B. L . (1990). Behavioral adaptation to pathogens and parasites: Five strategies. Neuroscience and Biobehavioral Reviews, 14, 273—294. Henderson, J. J. A., & Anglin, J. M . (2003). Facial attractiveness predicts longevity. Evolution and Human Behavior, 24, 351-356. Houston, V., & Bull, R. (1994). Do people avoid sitting next to someone who is facially disfigured? European Journal of Social Psychology, 24, 279-284. Hume, D. K., & Montgomerie, R. (2001). Facial attractiveness signals different aspects of "quality" in women and men. Evolution and Human Behavior, 22, 93-112. Jones, E. E., Farina, A., Hastorf, A. H., Markus, H., Miller, D. T., & Scott, R. A. (1984). Social stigma: The psychology of marked relationships. New York: Freeman. Kalick, S. M . , Zebrowitz, L. A., Langlois, J. H., & Johnson, R. M . (1998). Does human facial attractiveness honestly advertise health? Longitudinal data on an evolutionary question. Psychological Science, 9, 8-13. Kalish, C. W. (1996). Preschoolers' understanding of germs as invisible mechanisms. Cognitive Development, 11, 83-106. Katz, I. (1981). Stigma: A social psychological analysis. Hillsdale, NJ: Erlbaum. Kavaliers, M . , & Colwell, D. D. (1995). Discrimination by female mice between the odours of parasitized and non-parasitized males. Proceedings of the Royal Society of London B, 261, 31-35. Kurzban, R., & Leary, M . R. (2001). Evolutionary origins of stigmatization: The functions of social exclusion. Psychological Bulletin, 127, 187-208.  64 Langlois, J. H., & Roggman, L. A. (1990). Attractive faces are only average. Psychological Science, 1, 115-121. Loehle, C. (1995). Social barriers to pathogen transmission in wild animal populations. Ecology, 76, 326-335. Mancini, F., Gragnani, A., & D'Olimpio, F. (2001). The connection between disgust and obsessions and compulsions in a non-clinical sample. Personality and Individual Differences, 31, 1173-1180. Mulkens, S. A . N . , de Jong, P. J., & Merckelback, H. (1996). Disgust and spider phobia. Journal of Abnormal Psychology, 105, 464—468. Nunn, C. L., Altizer, S., Jones, K. E., & Sechrest, W. (2003). Comparative tests of parasite species richness in primates. The American Naturalist, 162, 597-614. Phillips, M . L., Young, A . W., Scott, S. K., Calder, A . J., Andrew, C , Giampietro, V., et al. (1998). Neural responses to facial and vocal expressions of fear and disgust. Proceedings of the Royal Society of London B, 265, 1809-1817. Pryor, J. B., Reeder, G. D., Yeadon, C , & Hesson-Mclnnis, M . (2004). A dual-process model of reactions to perceived stigma. Journal of Personality and Social Psychology, 87, 436^152. Rhodes, G., Zebrowitz, L. A., Clark, A., Kalick, S. M . , Hightower, A., & McKay, R. (2001). Do facial averageness and symmetry signal health? Evolution and Human Behavior, 22, 31-46. Rozin, P., Millman, L., & Nemeroff, C. (1986). Operation of the laws of sympathetic magic in disgust and other domains. Journal of Personality and Social Psychology, 50, 703-712.  65 Shackelford, T. K., & Larsen, R. J. (1997). Facial asymmetry as an indicator of psychological, emotional, and physiological distress. Journal of Personality and Social Psychology, 72, 456^166. Shackelford, T. K., & Larsen, R. J. (1999). Facial attractiveness and physical health. . Evolution and Human Behavior, 20, 71-7'6. Shapira, N . A., Liu, Y . , He, A . G., Bradley, M . M . , Lessig, M . C., James, G. A., et al. (2003). Brain activation by disgust-inducing pictures in obsessive-compulsive disorder. Biological Psychiatry, 54, 751-756. Solomon, G. E. A., & Cassimatis, N . L . (1999). On facts and conceptual systems: Young children's integration of their understandings of germs and contagion. Developmental Psychology, 35, 113-126. Stangor, C., & Crandall, C. S. (2000). Threat and the social construction of stigma. In T. F. Heatherton, R. E. Kleck, M . R. Hebl, & J. G. Hull (Eds.), The social psychology of stigma (pp. 62-87). New York: Guilford. Stark, R , Schienle, A., Walter, B., Kirsch, P., Sammer, G., Ott, TJ., et al. (2003). Hemodynamic responses to fear and disgust-inducing pictures; an fMRI study. International Journal of Psychophysiology, 50, 225-234. Thornhill, R., & Gangestad, S. W. (1999). The scent of symmetry: A human sex pheromone that signals fitness? Evolution and Human Behavior, 20, 175-201. Woody, S. R., & McLean, C., & Klassen, T. (2005). Disgust as a motivator of avoidance of spiders. Anxiety Disorders, 19, 461-275. Woody, S. R., & Teachman, B. A. (2000). Intersection of disgust and fear: Normative and pathological views. Clinical Psychology: Science and Practice, 7, 291-311.  Woody, S. R., & Tolin, D. F. (2002). The relationship between disgust sensitivity and avoidant behavior: Studies of clinical and nonclinical samples. Anxiety Disorders, 16, 543-559. Worden, B. D., Parker, P. G., & Pappas, P. W. (2000). Parasites reduce attractiveness and reproductive success in male gain beetles. Animal Behaviour, 59, 543-550. Zebrowitz, L. A., Fellous, J. M . , Mignault, A. & Andreoletti, C. (2003). Trait impressions as overgeneralized responses to adaptively significant facial qualities: Evidence from connectionist modeling. Personality and Social Psychology Review, 7, 194— 215.  67 Chapter 5. Empirical Test: Physical Disabilities as a Cue for Parasites  4  5.1. Introduction Despite publicly expressed tolerance, people often experience discomfort in the presence of individuals with physical disabilities. Negative reactions are evident in stereotypic beliefs about individuals with disabilities, in emotions such as disgust and anxiety, in attitudes and judgments such as the tendency to blame individuals for their disabling conditions, and in behavioral responses such as the tendency to physically avoid contact with disabled individuals (Ryan, 1971; Snyder, Kleck, Strenta, & Mentzer, 1979; Weinberg, 1976). Of course, the perception of disabilities elicits positive reactions as well, such as pity, compassion, and desires to be helpful. It's likely that many of the negative responses are automatic, whereas the positive responses involve reflective thought (Pryor, Reeder, Yeadon, & Hesson-Mclnnis, 2004). The discussion in the previous chapter suggests that these negative reactions may in part be a result of perceiving disabilities as a heuristic cue for parasites. If parasiterecognition mechanisms in fact respond to a broad range of morphological deviations from a normative standard, then people with amputated limbs or people who use wheelchairs may also activate these mechanisms. Although some historical and anecdotal evidence suggests that physical disabilities may be associated with parasites (individuals with disabilities have been perceived as unclean and have been socially excluded, Covey, 1998), little empirical research has rigorously investigated this possibility. There is, however, a large literature on people's responses to disabilities in A version of this chapter has been published separately: Park, J. H., Faulkner, J., & Schaller, M. (2003). Evolved disease-avoidance processes and contemporary anti-social behavior: Prejudicial attitudes and avoidance of people with physical disabilities. Journal of Nonverbal Behavior, 27, 65-87. Not all results reported in the published article are reported in this dissertation; but these findings are mentioned.  4  68 general, and the research findings appear to be consistent with the operation of parasiterecognition mechanisms. Research has found that people appear anxious during interactions with physically disabled individuals (Kleck, 1968; Sigelman, Adams, Meeks, & Purcell, 1986). Studies have also shown increased galvanic skin response in the presence of physically disabled others (Heinemann, Pellander, Vogelbusch, & Wojtek, 1981; Kleck, Ono, & Hastorf, 1966). Other studies have shown that interactions with facially disfigured individuals trigger specific patterns of cardiovascular activity (activation of the sympathetic-adrenalmedullary and the pituitary-adrenal-cortical axes), patterns that are typically associated with the perception of threat (Blascovich, Mendes, Hunter, Lickel, & Kawai-Bell, 2001). Perhaps the most revealing response toward disabled individuals is a very specific form of behavior: physical avoidance. Studies have found that adults physically distance themselves from individuals with physical disabilities or facial disfigurements (Heineman et al., 1981; Houston & Bull, 1994). Another study found that participants terminate interviews with a physically disabled confederate sooner, thereby physically removing themselves from the interaction (Kleck et al., 1966). In a cleverly designed study, Snyder et al. (1979) provided participants with the choice of sitting next to a confederate with or without a physical disability. Most participants actually chose to sit next to the disabled confederate when they had no face-saving justification for avoidance. However, when their avoidance could masquerade as a movie preference, an overwhelming majority chose not to sit next to the disabled confederate. Of course, many reasons may underlie negative reactions toward physically disabled individuals. These negative reactions are, however, consistent with the operation of parasite-recognition mechanisms. There has been other evidence more directly suggesting that physical disabilities may serve as a parasite cue. For instance,  69 individuals who are more concerned with parasites tend to have fewer friends with disabilities (Park, Faulkner, & Schaller, 2003). Another study found that the perception of other morphological deviations—such as facial birthmarks—automatically activates disease concepts (Duncan & Schaller, 2005).  5.2. Overview of Study and Specific Hypotheses Although negative responses to physically disabled individuals are consistent with the operation of parasite-recognition mechanisms, because physical disabilities may produce negative responses for conceptually distinct reasons, more direct evidence is necessary. In the present study, participants' reactions were assessed with the Implicit Association Test (IAT; Greenwald, McGhee, & Schwartz, 1998). A n IAT task was designed to assess the extent to which participants implicitly associated the category "disabled" with "disease." If indeed physical disabilities serve as a parasite cue, then 5  there should be evidence of this cognitive linkage (Hypothesis 1). It's possible, however, for the disabled-disease linkage to emerge as a result of psychological responses that are conceptually irrelevant to parasites. The semantic concept "disease" has a negative connotation, and disabled individuals may arouse negative thoughts for a variety of reasons (e.g., they may be perceived as nonreciprocators). Participants thus completed a second IAT task that assessed the extent to which physically disabled targets were implicitly linked to a broader class of unpleasant concepts. Because physical disabilities may serve as a cue not only for parasites, but also for other negative attributes, the perception of physical disabilities  Although the evolutionary reasons for responding to visible cues may have to do with parasites, the conceptual category "disease" was used in the IAT tasks because this category may better represent people's subjective experience. That is, people may more commonly think of others as "diseased" rather than as "parasite carriers." The implications of this method are discussed below. 5  70 may—for conceptually distinct reasons—activate both disease concepts and unpleasant concepts (which may also activate each other). In order to disentangle the operation of parasite-recognition mechanisms from other processes, additional methods were employed. Because the automatic activation of disease concepts may be moderated by additional fitness-relevant variables, the responses may be especially strong among individuals with temporarily or chronically heightened concerns about parasites. Also, given the possible role of disgust in behavioral avoidance, the responses may be especially strong among individuals who generally have a low threshold for disgust reactions. Therefore, prior to completing the IAT tasks, participants were introduced to an experimental manipulation that was intended to heighten their concerns about parasites. This manipulation was hypothesized to amplify disabled-disease associations (Hypothesis 2). In contrast, it was not expected to have much of an impact on disabledunpleasant associations (associations that may exist for reasons unrelated to parasiterecognition processes). Participants also completed measures of individual differences in concerns about parasites and in disgust sensitivity. Responses on these individualdifference measures were hypothesized to be correlated with disabled-disease associations (Hypothesis 3). In contrast, these responses were not expected to be correlated substantially with disabled-unpleasant associations.  , 5.3. Method Eighty-four university students (69 women, 15 men) participated in this study. Forty-three participants were of East Asian background, 29 were of European background, and 12 were of other ethnic backgrounds. After a practice IAT task, participants were introduced to a news-article manipulation. Under the guise of assessing impressions of news-based Web sites on the  71 Internet, participants were provided with a page allegedly printed from a Web site specializing in health news. The page contained five brief news items. Participants were asked to read the news items and to answer some questions assessing their reactions. Two versions of news article were used: One version contained news items pertaining specifically to the transmission of parasites (e.g., "Hepatitis A outbreak could hit Vancouver"), and the other version contained news items pertaining to parasite-irrelevant health matters (e.g., "Lifestyle changes can thwart diabetes"). A separate group of 55 students provided ratings for a set of words. The words were rated on how much they connoted disease and health, as well as on their pleasantness or unpleasantness. On the basis of these ratings, four sets of words were selected for the IAT tasks: five words that connoted health (healthy, hygienic, nutritious, strong, well); five words that connoted disease (contagious, epidemic, illness, infectious, sickness); five words that were rated as pleasant and irrelevant to health or disease (gentle, gift, rainbow, smart, trust); and five words that were rated as unpleasant and irrelevant to health or disease (evil, failure, hostile, nasty, ugly). The health words and the pleasant words were matched for their positivity; the disease words and the unpleasant words were matched for their negativity. Following the news-article manipulation, participants completed two IAT tasks. For one task (disabled-disease IAT), participants judged whether stimulus words (e.g., strong, contagious) connoted either health or disease, and also judged whether specific target persons (presented in photos) were either able-bodied or disabled. The target persons were real people who were either physically disabled (Terry Fox, Rick Hansen,  Stephen Hawking, Ototake Hirotada, Christopher Reeve) or not (Bono, Richard Dawkin Tom Hanks, Ralph Nader, Chan Ho Park). To ensure that participants knew that the disabled target persons posed no real threat of contagious disease, participants were  72 presented with brief biographical sketches of each stimulus person on the computer prior to the IAT task. The categorization trials in the IAT were divided into several blocks, and there were two critical blocks, consisting of 40 trials each. In one critical block, the response categories disabled and disease shared one response key on the keyboard, whereas ablebodied and health shared another response key. If disabled targets are associated with disease concepts, this response-key arrangement is psychologically consistent, resulting in shorter reaction times. In the other critical block of trials, disabled and health shared one response key, whereas able-bodied and disease shared another response key. If disability is associated with disease concepts, then this response-key arrangement is psychologically conflicting, resulting in longer reaction times. Therefore, the difference in average reaction times across the two blocks of trials serves as an indicator of implicit cognitive association (the IAT effect). Larger IAT effects in this task indicated stronger cognitive activation of disease concepts in response to perceptions of disabled targets. The second IAT task (disabled-unpleasant IAT) was procedurally identical, but a different set of stimulus words was used on the word-categorization trials. Participants categorized these words as either pleasant or unpleasant. Larger IAT effects in this task indicated stronger cognitive activation of unpleasant concepts in response to perceptions of disabled targets. The order of these two IAT tasks was counterbalanced. Participants also filled out self-report questionnaires assessing several individual differences: Perceived Vulnerability to Disease (PVD; Appendix E) includes 19 items assessing beliefs about personal susceptibility to disease and dislike for situations in which germ-transmission seems likely; Disgust Sensitivity (DS; revised from Haidt, McCauley, & Rozin, 1994; Appendix G) includes 32 items assessing the strength of the disgust response to a variety of potentially disgusting situations; and Belief in a  73 Dangerous World (BDW; Altemeyer, 1988; Appendix F) includes 12 items assessing concerns about violence and other social dangers that are unrelated to disease.  5.4. Results To calculate the IAT effects, the recommended scoring algorithm was used (Greenwald, Nosek, & Banaji, 2003). Positive values indicate a tendency to implicitly 6  associate disabled with disease and with unpleasant. Consistent with Hypothesis 1, there was an overall tendency to implicitly associate disabled with disease ( M = .66, p < .001). As expected, disabled was also associated with unpleasant (M= .6\,p < .001). The two IAT effects did not differ in strength (p = .29), and they were positively correlated with each other (r = .30, p < .01). Neither IAT effect was influenced by gender or ethnic background of participants (all ps > .35). Analyses revealed that the news-article manipulation had no impact on either disabled-disease or disabled-unpleasant associations (both ps > .50); thus, Hypothesis 2 was not supported. Hypothesis 3 was concerned with whether individual differences in Perceived Vulnerability to Disease (PVD) and Disgust Sensitivity (DS) may be predictive of the implicit associations. Both the P V D and DS scales comprise subscales that assess somewhat different aspects of disease vulnerability and disgust sensitivity. The P V D scale comprises the germ-aversion subscale (GA-PVD), which assesses discomfort with specific situations or behaviors through which disease-causing germs might be transmitted (e.g., "I prefer to wash my hands pretty soon after shaking someone's hand"), and the general-beliefs subscale (GB-PVD), which assesses general beliefs about personal susceptibility to disease (e.g., "In general, I think I am very susceptible to colds, This scoring algorithm became available after the publication of the article reporting this study. It was applied here for consistency with the other IAT results reported in the dissertation. 6  74 flu, and other infectious diseases"). The DS scale comprises four subscales assessing sensitivity to disgust in different domains. Overall, the disabled-disease association was correlated with a subscale of DS assessing disgust sensitivity in situations involving death and body envelope violations (r = .22, p = .05), consistent with Hypothesis 3. The disabled-unpleasant association was only weakly correlated with this DS subscale (r = .14, p = .21). However, these correlations did not significantly differ from each other (p>.50). Additional results emerged when participants were separated by cultural background. Although no specific hypotheses had been made regarding cultural differences, they are reported here because they may provide additional insight. Consider first the results for participants of European background (see Table 5.1). (These participants had lived in Canada for a mean of 20.1 years.) Individuals more wary of situations in which germs are transmitted (as indicated by their G A - P V D scores) were more likely to make disabled-disease associations (r = .36,/? = .06), consistent with Hypothesis 3. However, they showed an equally strong tendency to make disabled- . unpleasant associations as well (r = .31,p = .05). The results looked somewhat different among participants of East Asian background (see Table 5.2). (These participants had lived in Canada for a mean of 10.4 years.) Responses on the DS subscale assessing sensitivity in the presence of death and  Table 5.1 Correlations between Vulnerability Variables and IAT Effects (European Participants)  Germ-Aversion PVD General-Beliefs PVD Death & Body Envelope DS Belief in a Dangerous World Note, n = 29. * p < .05.  Disabled-Disease Association .36 .05 .01 .20  Disabled-Unpleasant Association .37* .09 .11 .27  75 Table 5.2  Correlations between Vulnerability Variables and IAT Effects (East Asian Participants)  Germ-Aversion PVD General-Beliefs PVD Death & Body Envelope DS Belief in a Dangerous World  Disabled-Disease Association  Disabled-Unpleasant Association  -.23 .29 .37* -.07  -.03 -.03 .19 .06  Note, n = 43. * p < .05. body envelope violations were moderately correlated with the disabled-disease associations (r = .37,p = .02), consistent with Hypothesis 3. There was a weaker correlation between the DS subscale and disabled-unpleasant associations (r= \9,p = .23). However, the difference in the magnitude of these correlations was not statistically significant (p = .32). Overall, there were results that were consistent with Hypothesis 3, but the evidence was not strong.  5.5. Discussion The results of this study provided only weak evidence for the hypothesis that physical disabilities may serve as a cue for parasites. Although participants did make disabled-disease associations (supporting Hypothesis 1), these were largely indistinguishable from disabled-unpleasant associations. Contrary to Hypothesis 2, a manipulation that was intended to amplify disabled-disease associations had no effect. There was partial support for Hypothesis 3, particularly when the sample was separated according to their ethnic background, but the effects were not clearly specific to disabled-disease associations. The methods used in this study paralleled those used in the study described in chapter 3. Therefore, similar methodological limitations and similar difficulties for finding support for the hypotheses apply here. One limitation was the use of the  76 categories "disease" in the disabled-disease IAT task. Although the conceptual category "disease" may include actual parasite carriers, it may also include individuals with disorders that are not contagious (e.g., individuals with cancer). Thus, the presence of disabled-disease associations itself does not provide strong support for the hypothesis that disabilities may serve as parasite cues (in other words, it's not at all surprising that disabled individuals—who may have noncontagious diseases—were associated with disease concepts). One way to address this problem is to use concepts that are more specific to parasites—for example, create IAT tasks that assess disabled-parasite associations, as well as disabled-disease associations. However, as noted in Footnote 5, such a method assumes that humans possess specialized functional cognitions specifically about parasites, which may be an unsound assumption. Additional methods that were intended to clarify the role of parasite-recognition mechanisms failed to do so. The lack of an effect of the news-articles manipulation may have been due to the fact that verbally presented information about pathogens does not have a strong impact. It's also possible that participants did not psychologically distinguish contagious and noncontagious health threats. This seems likely, given that intuitions about germs may not be very sophisticated. In hindsight, the difficulty of observing a distinction between disabled-disease and disabled-unpleasant associations might have been expected. Disease concepts and unpleasant concepts are not semantically independent; rather, disease concepts represent a subset of a broader category of unpleasant concepts. Given this overlap, it may have been difficult to observe the effects specified by Hypotheses 2 and 3. Indeed, disabled-disease and disabled-unpleasant associations were substantially correlated with each other (r = .30). These considerations suggest that methodologies that do not rely on measurements of semantic concepts may be more fruitful.  77 Results also suggested that there may be cultural differences in the relationships between the implicit associations and other individual-difference variables. Specifically, among participants of European background, concerns about the transmission of germs predicted disabled-disease and disabled-unpleasant associations. Among participants of East Asian background, disgust sensitivity (in situations involving death and body envelope violations) predicted disabled-disease associations. It's difficult to explain this cultural difference, but one possible explanation lies in the differences in cultural mythologies and belief systems pertaining to the etiology of ill health. Beliefs based on germ theory and interpersonal transmission have penetrated European cultures more deeply than East Asian cultures, which are more heavily influenced by the traditional tenets of Chinese medicine. East Asian ways of thought tend to attribute the presence of disease to internal rather than external factors (Wang, 1991). Consequently, Europeans' cognitive responses to physical disability may be more powerfully influenced by explicit thoughts about interpersonal transmission of germs, whereas East Asians' cognitive responses may be more directly linked to visceral affective reactions.  5.6. Conclusion The results of this study did not provide strong evidence for the hypothesis that physical disabilities may serve as a cue for parasites. But these results are best considered in conjunction with other research suggesting that physical disabilities may serve as parasite cues, such as research documenting avoidant responses toward disabled individuals and evidence indicating that people with heightened concerns about parasites have fewer friends with disabilities (Park et al., 2003). When considered together, the pattern of results across many studies suggest that disabilities may indeed serve as a heuristic cue for parasites, though perhaps not a strong cue. The present study, which is  78 the first to document an implicit cognitive link between disability and disease, adds a useful piece of empirical evidence to the overall body of literature on stigmatization of disabled individuals.  5.7. References Altemeyer, B. (1988). Enemies of freedom: Understanding right-wing authoritarianism. San Francisco: Jossey-Bass. Blascovich, J., Mendes, W. B., Hunter, S. B., Lickel, B., & Kowai-Bell, N . (2001). Perceiver threat in social interactions with stigmatized others. Journal of Personality and Social Psychology, 80, 253-267. Covey, H. C. (1998). Social perceptions ofpeople with disabilities in history. Springfield, IL: Thomas. Duncan, L. A., & Schaller, M . (2005). Unpublished data. University of British Columbia. Greenwald, A. G., McGhee, D. E., & Schwartz, J. L. K . (1998). Measuring individual differences in implicit cognition: The implicit association test. Journal of Personality and Social Psychology, 74, 1464-1480. Greenwald, A. G., Nosek, B. A., & Banaji, M . (2003). Understanding and using the implicit association test: I. A n improved scoring algorithm. Journal of Personality and Social Psychology, 85, 197-216. Haidt, J., McCauley, C , & Rozin, P. (1994). Individual differences in sensitivity to disgust: A scale sampling seven domains of disgust elicitors. Personality and Individual Differences, 16, 701-713. Heinemann, W., Pellander, F., Antje, V., & Wojtek, B. (1981). Meeting a deviant person: Subjective norms and affective reactions. European Journal of Social Psychology, 11, 1-25.  Houston, V., & Bull, R. (1994). Do people avoid sitting next to someone who is facially disfigured? European Journal of Social Psychology, 24, 279-284. Kleck, R. E. (1968). Physical stigma and nonverbal cues emitted in face-to-face interaction. Human Relations, 21', 19-28. Kleck, R. E., Ono, H., & Hastorf, A. H . (1966). The effects of physical deviance upon face-to-face interaction. Human Relations, 19, 425—436. Park, J. H., Faulkner, J., & Schaller, M . (2003). Evolved disease-avoidance processes and contemporary anti-social behavior: Prejudicial attitudes and avoidance of people with physical disabilities. Journal of Nonverbal Behavior, 27, 65-87. Pryor, J. B., Reeder, G. D., Yeadon, C., & Hesson-Mclnnis, M . (2004). A dual-process model of reactions to perceived stigma. Journal of Personality and Social Psychology, 87, 436-452. Ryan, W. (1971). Blaming the victim. New York: Pantheon. Sigelman, C. K , Adams, R. M . , Meeks, S. R., & Purcell, M . A . (1986). Children's nonverbal responses to a physically disabled person. Journal of Nonverbal Behavior, 10, 173-186. Snyder, M . L., Kleck, R. E., Strenta, A., & Mentzer, S. J. (1979). Avoidance of the handicapped: A n attributional ambiguity analysis. Journal of Personality and Social Psychology, 37, 2297-2306. Wang, J. - Y . (1991). Psychosomatic illness in the Chinese cultural context. In L . Romanucci-Ross, D. E. Moerman, & L. R. Tancredi (Eds.), The anthropology of medicine (2nd Ed., pp. 322-342). New York; Bergin & Garvey. Weinberg, N . (1976). Social stereotyping of the physically handicapped. Rehabilitation Psychology, 23, 115-124.  80 Chapter 6. Empirical Test: Obesity as a Cue for Parasites  6.1. Introduction Research suggests that various superficial oddities—such as cultural foreignness and facial birthmarks—may serve as heuristic cues for parasites (Duncan & Schaller, 2005; Faulkner, Schaller, Park, & Duncan, 2004). Also, as discussed in the previous chapter, there is a body of evidence (although somewhat equivocal) that is consistent with the hypothesis that physical disabilities may serve as a parasite cue. Perhaps the parasiterecognition system responds to a wide range of deviant morphology. If so, then it's possible that even deviant body shapes—such as extreme obesity—may trigger the system. Thus, an examination of obesity as a potential parasite cue provides a particularly interesting test of the generality of this particular cue-recognition system. Does previous research on reactions toward obese individuals provide any clues? Research has found that weight-based prejudice is widespread and takes the form of implicit stereotypes, expressed attitudes, behavioral avoidance, and other forms of discrimination (Bessenoff & Sherman, 2000; Crandall, 1994; Staffieri, 1967; Teachman, Gapinski, Brownell, Rawlins, & Jeyaram, 2003). The failure to avoid contact with fat people can itself be stigmatizing: Thin people are evaluated more negatively if they are simply seen with fat people (Hebl & Mannix, 2003). Previous investigations of the causes of antifat attitudes have focused on ideology and allied attribution processes. Specifically, fat people are perceived to violate selfdetermination ideologies; thus, individuals who more strongly endorse self-determination ideologies tend to be more prejudiced against fat people (Crandall, 1994). Moreover, the A version of this chapter is in preparation for publication: Park, J. H., Schaller, M , & Crandall, C. S. (in preparation). 7  81 impact of self-determination ideologies is mediated by perceivers' attributions about lack of willpower and personal responsibility. Individuals who believe that fat people lack willpower and are responsible for their weight are more likely to be prejudiced against them (Crandall & Martinez, 1996). However, some aspects of weight-based prejudice suggest components separate from ideology and attribution. Images of fat people sometimes arouse disgust (Harvey, Troop, Treasure, & Murphy, 2002), and fat people are commonly stereotyped as unattractive, unclean, and unhealthy—traits that are not clearly associated with willpower, but are associated with parasitic infection (Harris, Harris, & Bochner, 1982; NeumarkSztainer, Story, & Faibisch, 1998; Staffieri, 1967). Thus, it seems possible that weightbased prejudice is due, in part, to parasite-recognition processes. This chapter describes studies that explored this possibility.  6.2. Overview of Studies and Specific Hypotheses If obesity serves as a parasite cue, then several hypotheses can be deduced on the basis of principles described in previous chapters. First, perceivers' desire to avoid physical contact (e.g., touching) with obese individuals may be stronger than their desire to avoid nonphysical contact (e.g., talking on the phone), because physical contact with a parasite carrier is particularly harmful (Hypothesis 1). Second, because fitness-relevant variables may moderate parasite-recognition responses, perceivers with chronically heightened concerns about parasites may harbor stronger antifat attitudes. Moreover, this relationship may be especially strong under circumstances in which perceivers have had an opportunity to look at obese individuals, because visual perception of physical markers may be an important trigger for parasite-recognition processes (Hypothesis 2). Third, the perception of obesity may automatically activate disease concepts, and this  82 activation may be amplified among perceivers with heightened concerns about parasites (Hypothesis 3). These hypotheses were tested in five studies. Some of these studies were designed to investigate perceptions of fat people; other studies were designed to investigate conceptually distinct hypotheses but included measures pertinent to the present inquiry. For narrative coherence, this chapter is organized in three main parts (instead of five studies). Part 1 describes a study that tested Hypothesis 1: People's feelings of discomfort with coming into physical and nonphysical contact with obese individuals (and other targets of stigma) were assessed. Part 2 describes results from several studies that tested Hypothesis 2: Individual differences in concerns about parasites and in antifat attitudes were measured, and the relationship between the two variables was assessed. Part 3 describes a study that tested Hypothesis 3. In this study, the Implicit Association Test was used to assess the extent to which obese targets were implicitly associated with disease concepts. Participants were also introduced to a pathogen-salience manipulation to examine whether heightened concerns about parasites may amplify fat-disease associations.  6.3. Part 1: Physical versus Nonphysical Avoidance 6.3.1. Method. Forty-nine university students (41 women, 8 men) participated in this study. Thirty-six participants were of East Asian background, 12 were of European background, and 1 was of another background. To circumvent self-presentation biases, the primary measure was described as a "social knowledge questionnaire" and asked participants to "guess how an average student at U B C might feel" in various situations involving contact with stigmatized targets (Appendix H). This sort of indirect measure of individuals' beliefs and attitudes  83 has been successfully used in previous research (e.g., Devine, 1989). Participants responded on 10-point scales with endpoints labeled, 1 (the average student would be very comfortable) and 10 (the average student would be very uncomfortable). These responses served as rough indicators of participants' own feelings of discomfort. The targets included two individuals who may be argued as posing real threat to one's wellbeing, though for very different reasons: a woman with HIV and a man with a criminal record. There were also target individuals who are stigmatized on the basis of their appearance, although they pose no objective threat: a man with a facial birthmark, a man with an amputated leg, and an obese man. A picture of each target individual was provided in the questionnaire. Participants indicated how an average student might feel about "shaking hands," "talking on the phone," "hugging," and "exchanging emails" with these individuals. Two versions of questionnaires—counterbalancing the orders of target individuals and contact type—were used. O f the four different contact situations, two involve physical contact (shaking hands, hugging), and two involve nonphysical contact (phone conversation, exchanging email). For stigmatized targets posing parasite-irrelevant threats (e.g., criminal), there may be a general desire among participants to avoid any kind of contact (although the desire to avoid physical contact may be somewhat stronger, given the greater potential for harm). Thus, the criminal target served as a parasite-irrelevant threat control. On the other hand, for stigmatized targets posing parasite-relevant threats (e.g., person with HIV), participants' desire to avoid physical contact may be particularly strong because physical contact with a parasite carrier is particularly harmful. In contrast, there may be a weaker desire to avoid nonphysical contact with such targets. At one end, stigmatization of a person with HIV most obviously involves concerns about contagion (Bishop, Alva, Cantu, & Rittiman, 1991; Crandall, Glor, &  84 Britt, 1997), so it was predicted that participants would be especially motivated to avoid physical contact with this target. (Even though the target person with HIV displayed no visible markers, strong responses were expected because the self-report measure provided sufficient time for participants to engage in reflective thought.) At the other end, stigmatization of a person with a criminal record—who is perceived negatively for many reasons but none involving parasites and germs—most obviously does not involve a parasite-recognition component. Thus, it was predicted that participants would be motivated to avoid any kind of contact with this target and that any differential desire to avoid physical (versus nonphysical) contact would be relatively small. Accordingly, responses to these two targets serve as useful standards against which responses to the other targets could be compared. If responses to the other targets (birthmark, disability, obesity) resembled responses to the HIV target (but differ from responses to the criminal target), this may serve as suggestive evidence that these targets are perceived similarly to a person who clearly harbors harmful parasites (but differently from a person who is stigmatized for different reasons). 6.3.2. Results. Two measures of participants' feelings of discomfort were created for each target individual: A measure of discomfort with physical contact was created by averaging the responses in the "shaking hands" and "hugging" situations (mean r = .67), and a measure of discomfort with nonphysical contact was created by averaging the responses in the "phone conversation" and "exchanging email" situations (mean r = .56). The results are shown in Table 6.1. Several aspects of these results are noteworthy. First, participants were most uncomfortable interacting with the criminal target for both physical (M= 6.68) and nonphysical (M= 6.17) types of contact, and they were somewhat more uncomfortable with physical contact, t(4S) = 2.25,p = .03, d = .25. Participants also indicated high  85  Table 6.1 Feelings of Discomfort in Situations Involving Physical and Nonphysical Contact  Target and Type of Contact  Mean Level of SD Physical-Nonphysical Discomfort Discrepancy (Effect Size) 2.27 6.56 HIV - Physical HIV - Nonphysical 3.19 1.82 1.64 Criminal - Physical 6.68 1.84 Criminal - Nonphysical 6.17 2.15 .25 Birthmark - Physical 5.47 2.03 Birthmark - Nonphysical 2.72 1.69 •1.47„. Disabled - Physical 4.14 1.76 Disabled - Nonphysical 2.35 1.53 1.08 Obese - Physical 4.92 1.87 Obese - Nonphysical 2.79 1.82 1.15 Note. Mean levels of discomfort are based on a 10-point scale. Effect sizes are Cohen's ds, and different subscripted letters indicate significant differences between effect sizes (p < .05). a  d  c  c  discomfort for p h y s i c a l contact w i t h the H I V target m u c h lower for n o n p h y s i c a l contact  (M= 6.56), but  their d i s c o m f o r t was  (Af = 3.19), /(48) = 9.82,p < .001, d = 1.64.  F o r the  r e m a i n i n g targets characterized b y p h y s i c a l abnormalities (disability, b i r t h m a r k , obesity), participants i n d i c a t e d greater d i s c o m f o r t w i t h p h y s i c a l t h a n n o n p h y s i c a l contact  < .001, ds > 1.08).  (ps  T h e effect sizes o f these three targets were c l o s e r to that o f the H I V  target than the c r i m i n a l target. T o r i g o r o u s l y c o m p a r e the effect sizes, a series o f 2 x 2 repeated-measures analyses o f v a r i a n c e were c o n d u c t e d i n w h i c h the type o f target (e.g., H I V or c r i m i n a l ) and the type o f contact ( p h y s i c a l or n o n p h y s i c a l ) were within-subjects factors. T h e results o f s u c h analyses p r o v i d e d a means o f c o m p a r i n g the t w o g i v e n effect sizes. Regardless o f the m a i n effects, the absence o f a n interaction effect w o u l d suggest that responses to the t w o g i v e n targets f o l l o w the same basic pattern (i.e., the p h y s i c a l n o n p h y s i c a l discrepancies do not differ), whereas the presence o f a n interaction effect w o u l d suggest that the responses f o l l o w different patterns (i.e., the p h y s i c a l - n o n p h y s i c a l discrepancies do differ).  ;  86 A n analysis comparing the HIV target with the criminal target revealed an interaction effect, F(l,48) = 73.00,/? < .001, indicating that the effect size for the HIV target (d = 1.64) was clearly larger than that for the criminal target (d = .25). In other words, the discrepancy between discomfort with physical contact and discomfort with nonphysical contact with the HIV target was significantly greater than the analogous discrepancy for the criminal target. Additional analyses for the remaining pairs of effectsize comparisons revealed that the effect sizes for the disabled and obese targets did not differ significantly, but all remaining effect sizes differed from one another. The results of all 2 x 2 analyses of variance are presented in Table 6.2 (see also right-hand column of Table 6.1). 6.3.3. Discussion. Consistent with Hypothesis 1, the results showed that participants were more uncomfortable—as assessed by an indirect measure—with physical contact (relative to nonphysical contact) with an obese target. Although this physical-nonphysical discrepancy was not as large as that for a clearly contagious target (person with HIV), it was similar to those of birthmark and disabled targets. Also, the physical-nonphysical discrepancy for the obese target was clearly larger than that for the  Table 6.2 Results of All 2x2 Analyses of Variance: The Interaction Effects Comparison Targets F p_ < .001 73.00 HIV (1.64) and Criminal (.25) HIV (1.64) and Birthmark (1.47) 4.75 .03 HIV (1.64) and Disabled (1.08) 28.14 < .001 HIV (1.64) and Obese (1.15) 19.07 < .001 Criminal (.25) and Birthmark (1.47) 48.03 < .001 Criminal (.25) and Disabled (1.08) 28.57 < .001 Criminal (.25) and Obese (1.15) 28.24 < .001 Birthmark (1.47) and Disabled (1.08) 26.83 < .001 Birthmark (1.47) and Obese (1.15) 6.91 .01 Disabled (1.08) and Obese (1.15) 1.66 .20 Note. Significant interaction effect indicates that the physical-nonphysical discrepancy (effect size) for one target is significantly different from that of the other target.  87 parasite-irrelevant target (criminal). Although these results are consistent with the hypothesis, important methodological limitations should be noted. First, although there was a control target who posed a parasite-irrelevant threat, there was no control target who posed no threat at all (i.e., a healthy, "normal-looking" person). Such a no-threat control target is required to examine whether the physical-nonphysical discrepancies for the stigmatized targets emerge over and above a baseline level of discrepancy (because people may be less comfortable with physical contact with anyone, not just stigmatized individuals). Also, the sex of the target individuals was not controlled or manipulated (the HIV target was female, the remaining targets were male). Male and female participants may feel differently about contact with male and female targets. Indeed, in the case of physical contact with the HIV target, male participants reported less discomfort than did female participants (mean ratings of discomfort were 4.00 and 7.06, respectively). Future research needs to address these limitations.  6.4. Part 2: Concerns about Parasites and Dislike of Fat People Evolved cue-recognition mechanisms may be moderated by variables that bear on the functional utility of the mechanisms. One implication is that avoidant responses to individuals displaying heuristic parasite cues may be especially strong among individuals who, for whatever reason, have chronically heightened concerns about parasites. Consequently, chronically heightened concerns about parasites may predict dislike of fat people. I conducted five studies that included the Perceived Vulnerability to Disease (PVD; Appendix E) and the Anti-Fat Attitudes (AFA; Crandall, 1994; Appendix I) scales. The A F A scale comprises three subscales that assess (a) fear of becoming fat oneself, (b) attributions about fat persons' lack of willpower, and (c) dislike of fat people. The last  88  subscale (Dislike) offers a self-report measure of dislike of fat people; thus, correlations between P V D and Dislike would offer some evidence for the role of parasite-recognition mechanisms in prejudice against fat people.' There is another possible moderating variable: The relationship between P V D and Dislike may emerge especially strongly among perceivers who have had an opportunity to look at obese targets, because visual perception of physical markers may be an important component of parasite recognition. In other words, there may be an interaction effect of P V D and visual perception of obese targets on Dislike. 6.4.1. Method. In all five studies, participants completed the P V D scale before the A F A scale, and the two scales were separated by other measures or tasks. Before completing the A F A scale, some participants were exposed to pictures of obese targets, and some participants were not. In two studies (Studies 1 and 2), no participants viewed pictures of obese targets. In Study 1, participants completed IAT tasks (designed to test a conceptually distinct hypothesis) in which they were presented with pictures of Black and White target individuals and words connoting various positive and negative concepts (none relevant to disease). In Study 2, participants completed a task on the computer (designed to test a conceptually distinct hypothesis) in which they were repeatedly presented with pictures of faces that varied on several dimensions (female or male, Black or White, attractive or average) and were asked to respond when they perceived a change in some facial feature. In two additional studies (Studies 3 and 4), all participants viewed pictures of obese targets before completing the A F A scale. In Study 3, participants completed questionnaires that assessed their desire to avoid physical and nonphysical contact with various stigmatized targets (described above in section 6.3). In Study 4, participants completed IAT tasks that assessed the extent to which they associated obese targets with disease concepts (described below in section 6.5). And in the final study  89 (Study 5), participants completed questionnaires that attempted to indirectly measure their prejudicial attitudes toward various stigmatized targets (including obese individuals). In Study 5, exposure to pictures of obese targets was experimentally manipulated: Half of the participants viewed a picture of an obese target (embedded within a questionnaire) prior to completing the A F A scale, and half did not. 6.4.2. Results. It should be noted that the germ-aversion P V D subscale (GAPVD) is the clearest measure of concerns about parasite transmission, whereas the general-beliefs P V D subscale (GB-PVD) measures broader beliefs about one's susceptibility to disease. Indeed, responses on the G B - P V D subscale generally did not predict Dislike across all five studies (rs < .25, ps > .05). However, there were moderate to large positive correlations between G A - P V D and Dislike; and, consistent with Hypothesis 2, these correlations emerged most strongly among participants who had viewed pictures of obese targets (see Table 6.3). To test the interaction effect of G A - P V D and exposure to pictures of obese targets on Dislike, the regression method was employed. Data from all five studies were combined, and the variable representing exposure to images of obese targets (Pictures) was coded 1 (pictures-present condition) and -1 (pictures-absent condition). The pictures-present group consisted of 136 participants and the pictures-absent group  Table 6.3 Correlations Between Germ-Aversion PVD and Dislike of Fat People  Study Session and Sample Size Study 1, N = 35 Study 2, N = 87 Study 3, N = 47 Study 4, N = 60 Study 5, N = 57  Pictures of Obese Targets Present or Absent Absent Absent Present Present Present (n = 29) Absent (n = 28)  Correlations between GA-PVD and Dislike r=.11,p = .54 r = .06, p = .58 r = .38, p < .01 r=.47, p<.001 r = .43, p = .02 r=.36, p = .06  90 consisted of 150 participants. The G A - P V D scores were then centered by subtracting the mean from each score, and an additional predictor variable representing the G A - P V D x Pictures interaction effect was computed by taking the multiplicative product of these two variables. These three variables were entered simultaneously into a regression analysis in which the dependent variable was Dislike. The results showed that, across all participants, G A - P V D predicted Dislike (P = .26, p < .001). However, this relationship was qualified by a G A - P V D x Pictures interaction effect, t(2S2) = 2.49,/? = .01. Figure 6.1 illustrates this interaction effect. . Among participants in the pictures-present condition, P V D - G A had a substantial positive relation with Dislike (r= .38,/? < .001). In contrast, among participants in the picturesabsent condition, P V D - G A had a much weaker relation with Dislike (r - .12, p = .13). A l l participants had also completed the Belief in a Dangerous World (BDW; Altemeyer, 1988; Appendix F) scale, which measures concerns about parasite-irrelevant threats.  1  2  3  4  5  6  7  Perceived Vulnerability to Disease (Germ Aversion)  Figure 6.1. Regression lines indicating predictive effects of Perceived Vulnerability to Disease (Germ-Aversion Subscale) on dislike of fat people, in the pictures-present and pictures-absent conditions.  91 B D W was also correlated with Dislike (r = .17, p < .01), suggesting the possibility that the relation between P V D - G A and Dislike may be explained not by concerns about parasites specifically, but by sensitivity to threats in general. Thus, an additional regression analysis was performed in which B D W was also included as a predictor variable. The inferential results reported above did not change; but the predictive effect of B D W was reduced (0 = .08, p = . 17). 6.4.3. Discussion. These results are consistent with the hypothesis that chronic concerns about parasites may predict antifat attitudes and that this relationship may be especially strong following visible perception of obese targets. However, these results should be interpreted with caution, given that exposure to pictures of obese targets was not experimentally manipulated across all study samples. As is often the case in the absence of experimental manipulations, there are potential confounds: In Studies 1 and 2, not only were there no pictures of obese targets, there was no mention at all of obese individuals (except in the A F A scale). On the other hand, Studies 3, 4, and 5 were more explicitly investigating attitudes toward obese individuals, which likely increased the salience of obese individuals. In the one study in which exposure to pictures of obese targets was experimentally manipulated (Study 5), the size of the correlations between G A - P V D and Dislike across the two groups (rs = .43 and .36) did not differ from each other (p > .50), casting further doubt on the role of visual perception. But even i f an obesity-salience confound played a role, there is a broader argument that remains intact: The relationship between concerns about parasites and dislike of fat people may require some additional trigger, something that "releases" unfavorable attitudes toward fat people. Whether this trigger is visual perception of obese individuals or whether other factors are also involved remains unclear. The take-  92 home point is that these are the first empirical findings to implicate individual differences in concerns about parasites as a predictor of antifat attitudes.  6.5. Part 3: Implicit Associations between Fat and Disease If obesity serves as a parasite cue, the perception of obesity may automatically activate disease concepts, and this activation may be especially strong among individuals with heightened concerns about parasites. A study employing the Implicit Association Test (IAT; Greenwald, McGhee, & Schwartz, 1998) was conducted to test this hypothesis. Because the IAT methodology has been described in previous chapters, I omit the details here. It was hypothesized that "fat" and "disease" would be implicitly associated (Hypothesis 3 a). However, because obesity may serve as a cue for different kinds of negative attributes (e.g., lack of willpower), the presence of fat-disease associations on its own would not provide strong evidence for the hypothesis that obesity serves as a parasite cue. Participants thus completed a second IAT task that assessed fat-unpleasant associations, and additional methods were employed to disentangle the fat-disease and fat-unpleasant associations. Because parasite-recognition mechanisms may be functionally flexible, any contextual information suggesting increased vulnerability to parasites may amplify fat-disease associations more than fat-unpleasant associations (Hypothesis 3b). To test this hypothesis, an experimental manipulation was introduced immediately before the IAT tasks: Some participants were exposed to images that made pathogens especially salient (this manipulation has been successfully used in previous research, Faulkner et al., 2004). Participants also completed measures of individual differences in concerns about parasites and in disgust sensitivity. It was hypothesized  93 that responses on these measures would predict fat-disease associations more strongly than fat-unpleasant associations (Hypothesis 3c). 6.5.1. Method. Sixty university students (47 women, 13 men) participated in this study. Thirty-four participants were of East Asian background, 18 were of European background, and 8 were of other ethnic backgrounds. After a practice IAT task, participants were introduced to a slide-show manipulation. Participants were randomly assigned to watch one of three slide shows on a computer screen. One slide show {pathogens condition) was designed to make infectious pathogens especially salient. It consisted of 10 images portraying germs, infections, and the prevalence of disease-causing pathogens (e.g., one slide depicted germs lurking in kitchen sponges and family pets; another showed a microscopic photograph of a human surrounded by bacteria). The second slide show (accidents condition) was designed to make a pathogen-irrelevant health threat especially salient. It consisted of 10 images depicting accidents, hazards, and other non-disease-related health threats (e.g., electrocution in the bathtub). Finally, the third slide show (work ethic condition) presented 10 images that made salient the value of hard work. The latter two slide shows represented different types of control conditions. To the extent that implicit associations in the pathogens condition are stronger than those in the accidents condition, these results may be attributed specifically to the salience of pathogens rather than to a more general concern with personal safety and well-being. To the extent that implicit associations in the pathogens condition are stronger than those in the work ethic condition, the results implicate effects independent of another process that has been previously linked to antifat attitudes. (Moreover, the inclusion of this work ethic condition allowed an independent test of the extent to which the salience of the selfdetermination ideology also influences implicit associations.)  94 Following the slide show, participants completed two IAT tasks. The tasks were essentially identical to those described in chapter 5; the key difference was that fat and thin targets replaced disabled and able-bodied targets. For one task {fat-disease IAT), participants judged whether stimulus words (same as those in chapter 5) connoted either health or disease, and they also judged whether specific target persons (presented in photos) were either thin or fat. These photos were 10 dieters' before-and-after photos taken from a Web site for a weight-loss program (8 women, 2 men); therefore, the fat and thin targets were actually the same people. Only individuals who lost over 100 pounds in the weight-loss program were included as stimulus persons. The other task (fatunpleasant IAT) was procedurally identical, but a different set of stimulus words was used on the word-categorization trials. These words were strongly evaluative but largely irrelevant to disease and health; participants categorized them as either pleasant or unpleasant. As described previously, larger IAT effects indicated stronger cognitive activation of disease and unpleasant concepts in response to perceptions of fat people. The order in which participants completed these two IAT tasks was counterbalanced. For half of the participants, the fat-disease IAT immediately followed the slide show manipulation. For the rest of the participants, the fat-unpleasant IAT immediately followed the slide show manipulation. Participants also completed measures of Perceived Vulnerability to Disease (PVD; Appendix E) and Disgust Sensitivity (DS; revised from Haidt, McCauley, & Rozin, 1994; Appendix G). 6.5.2. Results. The recommended scoring algorithm was used to calculate the IAT effects (Greenwald, Nosek, & Banaji, 2003). Consistent with Hypothesis 3a, there was an overall tendency to associate fat people with disease (M= .51,p < .001). There was also a tendency to associate fat people with unpleasant (M= .60, p < .001). Results showed that the fat-unpleasant IAT effect was somewhat stronger than the fat-disease  95 IAT effect, /(59) = 2.11, p < .01, d = .36, and the two IAT effects were highly correlated with each other (r = .59, p < .001). Neither IAT effect was influenced by gender or ethnic background of participants (all ps > .05). Hypothesis 3b was concerned with whether the implicit associations may be influenced by the slide-show manipulation. The effects of this manipulation were expected to be short-lived. Because the IAT order was counterbalanced, the type of IAT task completed first—immediately after the slide show—can be treated as a separate Q  independent variable. Primary analyses focused on that first IAT task. A 2 x 3 (IAT type x slide show) analysis of variance revealed an interaction effect, F(2,54) = 3.32, p = .04. The slide-show manipulation exerted an effect on implicit associations, but this effect differed across the two different IAT tasks (see Figure 6.2).  • Pathogens Salient • Accidents Salient • Work Ethic Salient  Fat-Disease IAT  Fat-Unpleasant IAT  IAT Task  Figure 6.2. Effect of slide-show manipulation on implicit associations linking fat people to disease (fat-disease IAT) and to unpleasant (fat-unpleasant IAT).  Additional analyses on the second IAT task revealed no effects of the slide show manipulation. These noneffects (coupled with the effects on thefirsttask) reveal that the impact of temporarily heightened concerns about pathogens is indeed quite temporary. 8  96 There are a couple of different ways to deconstruct this interaction effect. Participants in the pathogens condition were expected to be especially likely to associate fat with disease. Planned contrasts showed that fat-disease associations were stronger in the pathogens condition ( M = .72) than in the accidents and work ethic conditions (Ms = .53 and .47), r(28) = 1.83,/? = .08. On the other hand, the less specific fat-unpleasant associations were stronger in the work ethic condition (M= .76) than in the pathogens and accidents conditions (Ms = .54 and .60), r(28) = 2.05,p = .05. Furthermore, analysis of simple main effects revealed that within the pathogens condition, fat-disease associations were stronger than fat-unpleasant associations, although this differences was not statistically significant, F(l,54) = \ .95,p = Al,d=  .60. Thus, Hypothesis 3b was  partially supported. Finally, contrary to Hypothesis 3 c, neither concerns about parasites nor disgust sensitivity positively predicted fat-disease associations. Instead, a somewhat puzzling result was observed. Among participants of European background (n = 18), responses on the germ-aversion subscale of Perceived Vulnerability to Disease (GA-PVD) were negatively correlated with fat-disease associations (r = ^48, p = .04). Among participants of East Asian background, G A - P V D was not correlated with either IAT effect (n = 34; both rs < .08, both ps > .60). The negative relationship between G A - P V D and the fat-disease associations (among the European participants) is in direct contrast to the positive relationship between G A - P V D and disabled-disease associations reported in chapter 5. This is difficult to explain, but an explanation may be premature given that the finding was based on a sample of 18 participants. 6.5.3. Discussion. The results of this study provided mixed results. Participants associated fat with disease, supporting Hypothesis 3a. Fat-disease associations were amplified by the pathogen-salience manipulation, but this effect was not strong,  97 providing partial support for Hypothesis 3b. There was no support for Hypothesis 3c: Individual differences in concerns about parasites and in disgust sensitivity were not positively correlated with fat-disease associations. This study, like the IAT study described in chapter 5, has some methodological limitations. Because obesity may be perceived negatively for many reasons, the presence of fat-disease associations on its own is not highly informative (indeed, results showed that fat-unpleasant associations were somewhat stronger). Additional methods that were intended to clarify the role of parasite-recognition mechanisms provided mixed results. As discussed in the previous chapter, disease concepts and unpleasant concepts are not semantically independent, but are highly related. Given this overlap, it may have been difficult to observe the effects specified by Hypotheses 3b and 3c. Indeed, results showed that fat-disease and fat-unpleasant associations were highly correlated with each other (r = .59). Thus, it is significant that the slide-show manipulation had the impact that it did. There is, however, an alternative explanation for the effect of the slide-show manipulation. Participants exposed to images of pathogens were likely reminded about the negativity of disease. And because fat people tend to be associated with negative concepts in general, the manipulation may have increased fat-disease associations simply by increasing the tendency to associate one negative thing with another. According to this explanation, the pathogen-salience manipulation may increase the tendency to associate anything negative (e.g., evil, death) with disease concepts. This explanation is plausible, and unfortunately, the design of this study does not afford a way to rule it out. A study that could rule out this explanation requires control IAT tasks in which participants categorize other positive-negative categories (e.g., good and evil) in addition to thin and fat. Of course, given the methodological limitations of the IAT noted above,  98 alternative methods might more fruitfully be employed to test the hypothesis that obesity may serve as a parasite cue.  6.6. General Discussion Results from several studies, employing different methodologies, provided some support for the hypothesis that obesity may serve as a heuristic cue for parasites. Although each study has some weakness, across the entire set of studies, a relatively consistent pattern of findings supports the general hypothesis that obesity may serve as a cue for parasites. By providing some evidence that obesity may serve as a parasite cue, these findings demonstrate the scope and automaticity of parasite-recognition mechanisms: Unlike with many other physical stigmas, no rational argument implicates obesity as a sign of pathogen presence (i.e., it's difficult to argue coherently that being near an obese person endangers one's health). These findings also highlight a potentially important cause of weight-based prejudice; and identifying causes of prejudice is the first step toward reducing it. It goes without saying that the findings reported in this chapter—and the interpretation of them—do not imply that prejudice against fat people is an evolutionarily adaptive response. Parasite-recognition mechanisms are biased toward false-positive errors; these findings demonstrate just how extensive this bias may be. By the same token, extreme thinness (displayed by people with anorexia, for example) may also trigger parasite-recognition mechanisms. And because individuals must learn many of the cues associated with parasites, as well as what constitutes "normal" appearance, the point at which a body size is considered abnormally large (or small) may be influenced by local cultural standards.  99 6.7. Broader Implications of Parasite-Recognition Mechanisms The investigations described in chapters 5 and 6 were not intended simply to find evidence for parasite-recognition mechanisms; they were also intended to identify causes of well-documented stigmas. The possibility that morphological deviations may serve as parasite cues has important implications for understanding the psychology of stigma. Most existing explanations of stigma invoke general psychological tendencies to derogate other people—such as individuals' need to maintain their self-esteem or to view their ingroup positively (for review, see Crocker, Major, & Steele, 1998). As Neuberg, Smith, and Asher (2000) noted, these sorts of explanations have limited value: "If you want to feel better about yourself, for instance, you could ostensibly denigrate anyone. Why, then, do members of North American society stigmatize ethnic minorities, people with AIDS, and child molesters, but not people with protruding belly buttons?" (p. 33, emphasis in the original). Goffman (1963) described three types of stigma in particular: abominations of the body, blemishes of individual character, and tribal stigmas. A similar typology recurs in other analyses of stigma, and it seems that qualitatively distinct emotions—rather than a general negativity—are associated with different types of stigma (e.g., Kurzban & Leary, 2001; Neuberg et al., 2000). Most notably, many researchers have singled out physical abnormality—and its visibility—as a major source of stigmatization (Crocker et al., 1998; Goffman, 1963; Jones et al., 1984). Why are stigmas based on appearance so pervasive? Answers such as "because society deems certain features to be unattractive and devalues them" only raise more questions. Why does society devalue unattractiveness? How do people decide which features are unattractive in the first place? Some answers to these questions are provided by an evolutionary perspective outlining the consequences of parasite-recognition mechanisms.  100 Researchers often emphasize the socially defined nature of stigma to highlight the fact that no attribute is intrinsically stigmatizing, but rather, that any attribute can become stigmatized depending on the social context. As Jones et al. (1984) noted, "The stigmatizing process is relational.... What is deviant in one culture or subgroup may be the norm in another" (p. 5). Indeed, the degree to which various atypical characteristics (e.g., "deviant" sexual practices) are stigmatized is context dependent (Archer, 1985). The point that stigmatization is a subjective phenomenon that involves the perceiver's mind as well as the target's features is well taken. But this means that we need to better understand perceivers' psychological mechanisms involved in stigmatization; it does not mean that stigmas are arbitrary social constructions. At a deeper level, it's clear that stigmas are not socially constructed on a whim. Some features are more readily and more universally stigmatized than others: "Although being male and being fat are both attributes that may elicit stigmatization in some social contexts, the stigma associated with fatness is much more pervasive, and more difficult to escape" (Crocker et al., 1998, p. 506). Why is this? Along with other research on functional social exclusion, the present research offers some answers.  6.8. Conclusion The studies described in this chapter found some evidence for the hypothesis that obesity may serve as a heuristic cue for parasites. These are the first empirical investigations that tested whether—in addition to other contributors—parasiterecognition mechanisms may contribute to weight-based prejudice. Although the studies had some limitations, the results as a whole were generally consistent with the hypothesis that obesity may serve as a parasite cue.  101 6.9. References Archer, D. (1985). Social deviance. In G. Lindzey & E. Aronson (Eds.), The handbook of social psychology (3rd ed., pp. 743-804). New York: Random House. Bessenoff, G. R , & Sherman, J. W. (2000). Automatic and controlled components of prejudice toward fat people: Evaluation versus stereotype activation. Social Cognition, 18, 329-353. Bishop, G. D., Alva, A . L., Cantu, L., & Rittiman, T. K . (1991). Responses to persons with AIDS: Fear of contagion or stigma? Journal of Applied Social Psychology, 21, 1877-1888. Crandall, C. S. (1994). Prejudice against fat people: Ideology and self-interest. Journal of Personality and Social Psychology, 66, 882-894. Crandall, C. S., Glor, J., & Britt, T. W. (1997). AIDS-related stigmatization: Instrumental and symbolic attitudes. Journal of Applied Social Psychology, 27, 95-123. Crandall, C. S., & Martinez, R. (1996). Culture, ideology, and antifat attitudes. Personality and Social Psychology Bulletin, 22, 1165-1176. Crocker, J., Major, B., & Steele, C. (1998). Social stigma. In D. T. Gilbert, S. T. Fiske, & G. Lindzey (Eds.), The handbook of social psychology (4th ed., pp. 504-553). New York: McGraw-Hill. Devine, P. G. (1989). Stereotypes and prejudice: Their automatic and controlled components. Journal of Personality and Social Psychology, 56, 5-18. Duncan, L. A., & Schaller, M . (2005). Unpublished data. University of British Columbia. Faulkner, J., Schaller, M . , Park, J. H., & Duncan, L. A . (2004). Evolved diseaseavoidance mechanisms and contemporary xenophobic attitudes. Group Processes and Intergroup Relations, 7,333-353.  102 Goffman, E. (1963). Stigma: Notes on the management of spoiled identity. Englewood Cliffs, NJ: Prentice-Hall. Greenwald, A . G., McGhee, D. E., & Schwartz, J. L. K . (1998). Measuring individual differences in implicit cognition: The Implicit Association Test. Journal of Personality and Social Psychology, 74, 1464-1480. Greenwald* A. G., Nosek, B. A., & Banaji, M . (2003). Understanding and using the implicit association test: I. A n improved scoring algorithm. Journal of Personality and Social Psychology, 85, 197-216. Haidt, J., McCauley, C , & Rozin, P. (1994). Individual differences in sensitivity to disgust: A scale sampling seven domains of disgust elicitors. Personality and Individual Differences, 16, 701-713. Harris, M . B., Harris, R. J., & Bochner, S. (1982). Fat, four-eyed and female: Stereotypes of obesity, glasses and gender. Journal of Applied Social Psychology, 6, 503-516. Harvey, T., Troop, N . A . , Treasure, J. L., & Murphy, T. (2002). Fear, disgust, and abnormal eating attitudes: A preliminary study. International Journal of Eating Disorders, 32, 213-218. Hebl, M . R., & Mannix, L. M . (2003). The weight of obesity in evaluating others: A mere proximity effect. Personality and Social Psychology Bulletin, 29, 28-38. Jones, E. E., Farina, A., Hastorf, A . H., Markus, H., Miller, D . T., & Scott, R. A. (1984). Social stigma: The psychology of marked relationships. New York: Freeman. Kurzban, R., & Leary, M . R. (2001). Evolutionary origins of stigmatization: The functions of social exclusion. Psychological Bulletin, 127, 187-208. Neuberg, S. L., Smith, D. M . , & Asher, T. (2000). Why people stigmatize: Toward a biocultural framework. In T. F. Heatherton, R. E. Kleck, M . R. Hebl, & J. G. Hull (Eds.), The social psychology of stigma (pp. 31-61). New York: Guilford.  Neumark-Sztainer, D., Story, M . , & Faibisch, L. (1998). Perceived stigmatization among overweight African-American and Caucasian adolescent girls. Journal of Adolescent Health, 23, 264-270. Staffieri, J. R. (1967). A study of social stereotypes of body image in children. Journal of Personality and Social Psychology, 7, 101-104. Teachman, B . A., Gapinski, K. D., Brownell, K. D., Rawlins, M . , & Jeyaram, S. (2003). Demonstrations of implicit anti-fat bias: The impact of providing causal information and evoking empathy. Health Psychology, 22, 68-78.  104 Chapter 7. Summary and Some Final Thoughts  7.1. Summary of Empirical Findings Theoretical considerations suggested that, in response to recurrent adaptive problems, humans may have evolved specific cue-recognition mechanisms. I focused on two sets of mechanisms in particular: kin-recognition mechanisms and parasiterecognition mechanisms. Theoretical analyses suggested that cue recognition may sometimes break down, resulting in erroneous responses to heuristic cues. Theoretical analyses also suggested that the extent to which cues may activate functional cognitions and emotions may be moderated by various contextual and personological factors. These considerations led to a number of hypotheses concerning how people may perceive others in contemporary contexts, which I tested in a number of studies. Below, I summarize the empirical findings and discuss some of the implications. 7.1.1. Attitude similarity as a cue for kinship. In the study described in chapter 3, I tested the hypothesis that attitude similarity may serve as a heuristic cue for kinship. In this study, participants were presented with two individuals—one depicted as attitudinally similar, the other depicted as dissimilar. Results showed that participants implicitly associated the similar other with family concepts. Participants also associated the similar other with pleasant concepts in general, but the similar-family and similarpleasant associations were separable to some extent. Individual differences in the tendency to respond intuitively were more likely to predict similar-family associations. In addition, similar-family associations were more likely to predict self-reported prosoeial inclinations toward the similar target. These findings suggest that people may be more empathic and prosoeial toward similar others because similarity signals—among other things—kinship. However, the results of this study are also consistent with  105 alternative hypotheses. For instance, it's possible that the semantic concept "family" includes not only genetic kin, but other close relations as well. Thus, in order to examine the role of kin-recognition mechanisms in interactions between strangers, it's important to first attain a more refined understanding of human kin-recognition mechanisms. 7.1.2. Physical disabilities as a cue for parasites. In the study described in chapter 5,1 tested the hypothesis that physical disabilities may serve as a cue for parasites. The results showed that participants implicitly associated disabled individuals with disease concepts. But because disabilities may serve as a cue for other negative attributes, it's important to show that disabled-disease associations are distinct from disabledunpleasant associations. However, the disabled-disease associations were largely indistinguishable from disabled-unpleasant associations. As is often the case, the lack of effects is difficult to interpret. It's possible that the methods used in this study were not appropriate for the questions that were investigated. In particular, methods that rely on semantic concepts may not be appropriate for testing the operation of parasite-recognition mechanisms. It's also possible that parasite-recognition mechanisms overlap to a large extent with other mechanisms that process information about other threats (see below). The findings of this study are best considered in conjunction with other evidence suggesting that physical disabilities may serve as a parasite cue. Clearly, more research is needed to investigate this hypothesis. 7.1.3. Obesity as a cue for parasites. In the studies described in chapter 6,1 tested the hypothesis that obesity may serve as a cue for parasites. These studies were organized in three parts, each addressing a specific question. Part 1 described a study that tested the hypothesis that people may be especially uncomfortable coming into physical contact with obese individuals. Although the results supported the hypothesis, the findings may have been more informative if the study had included a no-threat control  106 target. In Part 2, results from several studies showed that there is a positive correlation between chronically heightened concerns about parasites and antifat attitudes. As hypothesized, this relationship was especially strong among participants who had viewed pictures of obese targets. More research should be conducted to test this hypothesis more rigorously (e.g., exposure to pictures of obese targets should be experimentally manipulated). Part 3 described a study that tested the hypothesis that the perception of obesity may automatically activate disease concepts, and that this activation may be moderated by fitness-relevant variables. The results revealed that participants implicitly associated fat with disease, and this appeared to be amplified by a manipulation that made the threat of pathogens more salient. However, individual differences in concerns about parasites were not related to fat-disease associations in a straightforward manner. Overall, although there were some odd and inexplicable results, there was a relatively consistent pattern of findings implicating obesity as a parasite cue. 7.1.4. Implications of the empirical findings. What are some of the implications of these findings (and nonfindings)? Some of the findings that supported the hypotheses may provide a more nuanced understanding of social cognitive processes. For instance, our reactions to other people may not be merely positive or negative; rather, qualitatively distinct thoughts and feelings may underlie our reactions. The fact that several hypotheses were not supported (or only weakly supported) may reflect methodological weaknesses as well as the limitations of the theoretical framework. Methods relying on people's verbal abilities (the Implicit Association Test) may not be ideal for testing the impact of cues on functional cognitions. A t a theoretical level, conceptual categories (e.g., disease, unpleasant) may not be as distinct or delimited as initially assumed. If so, we may need to re-examine the presumed characteristics of evolved psychological mechanisms (e.g., Ohman & Mineka, 2001). To what extent can we assert that evolved  107 mechanisms are encapsulated i f concepts that are hypothesized to be psychologically distinct are not in fact distinct? Also, if features such as similarity and obesity can serve as cues for multiple attributes, to what extent can we assert that evolved mechanism are characterized by selectivity? Of course, a single feature that is highly correlated with multiple kinds of fitness-relevant attributes could theoretically serve as a cue for multiple systems. If so, documenting the impact of a particular cue on a particular recognition mechanism is likely to be challenging, as seen in the studies described above. Although few sex differences were found, the studies generally lacked sufficient sample sizes to find effects of sex. But given that many evolved mechanisms may operate differently in males and females, future research should be more attentive to this variable, both conceptually and methodologically. Some cultural differences (based on participants' cultural background) were observed in one study (chapter 5), but not in others. However, many of these studies did not have sufficient sample sizes for cross-cultural comparisons; thus, it's possible that cultural differences exist for processes such as kin recognition. Finally, it should be noted that the present studies addressed only a limited set of questions pertaining to the impact of heuristic cues (attitude similarity, physical disabilities, obesity); they did not test the validity of the broader models of kin recognition and parasite recognition (which already have substantial empirical support). And these studies certainly did not test the validity of the evolutionary perspective.  7.2. Additional Issues and Questions In addition to the unresolved issues in this dissertation, there are additional intriguing questions for future research. I explore some of them for each set of cuerecognition mechanisms.  108 7.2.1. Kin-recognition mechanisms. One implication of Hamilton's (1964) rule is that genetically closer kin may arouse stronger nepotism. But our intuition tells us that kinship is not just a matter of the degree of relatedness; rather, different kin relationships feel qualitatively different. Consider our own nepotistic tendencies. Among the different kinds of kin relationships, the largest amount of investment is found in parent-offspring relationships (and more specifically, investment flows from parents to offspring). Genetically, offspring and siblings are equivalent (the probability of sharing a given gene with an offspring and with a sibling is the same). But behaviorally and psychologically, offspring and siblings are clearly not the same. Measured either in terms of nepotistic behavior or in terms of subjective closeness, the parent-offspring relationship is more powerful (Essock-Vitale, & McGuire, 1985; Stewart, 1983). Organisms may therefore possess distinct psychological mechanisms for distinct kin relationships. The evolutionary reasons for such distinct mechanisms are likely complex. One obvious difference between offspring and siblings is that one's relatedness to offspring is—at least for mothers—more certain, which likely contributed to the evolution of especially powerful nepotistic responses among mothers toward offspring. It's possible that additional cues and mechanisms are involved in nepotism directed toward offspring. Specifically, cues of young age may trigger strong prosocial tendencies (especially when combined with other kinship cues). Indeed, people report greater willingness to help younger kin, especially infants (Burnstein, Crandall, & Kitayama, 1994). More broadly, research shows that humans and nonhuman animals display favorable responses to infants: The presence of infants triggers maternal responses in female rats, and human adults prefer pictures of babies to pictures of adults (Zebrowitz, 1997). A n interesting implication is that, separate from the kinship cues discussed in this dissertation, cues for young age may additionally activate kin-  109 recognition and prosoeial responses. There is indeed evidence that adults with "babyfaces" are treated more favorably (Keating, Randall, Kendrick, & Gutshall, 2003). This may be an instance of a different kind of false-positive error (responding to nonbaby as baby). If processes underlying parental care and sibling care are indeed psychologically distinct, this raises additional questions. Are there specific kin-recognition mechanisms for other kinds of kin? For instance, are there specific psychological mechanisms that mediate nepotistic behavior toward nephews, nieces, cousins, and grandchildren? The present state of knowledge does not provide clear answers. There is another important issue concerning kin-recognition mechanisms. The perception of kinship in fact produces two distinct responses: nepotism and incest avoidance. Many kinship cues that produce one response also produce the other (e.g., early coresidence leads to both altruism and aversion to sex). This raises a quandary. Conventional wisdom—along with a large body of psychological literature—indicates that similarity is a key contributor to attraction between individuals (for review, see Berscheid & Reis, 1998). However, DeBruine (2005) found that facial similarity enhances trust but reduces sexual attraction (consistent with incest-avoidance motivations). But there's more to the story. The reduction in sexual attraction was found only when participants were considering a short-term relationship. (For a discussion of how long-term and short-term relationships may have different evolutionary bases, see Buss & Schmitt, 1993.) When considering a long-term relationship, facial similarity wasn't considered aversive (though it wasn't considered attractive either). Clearly, similarity between long-term couples—especially along dimensions such as attitudes—is likely to confer benefits associated with compatibility, which may offset any incestrelated aversion.  110 This opens up more avenues for research. Within the context of altruism, the presence of heuristic kinship cues may have a fairly linear relationship with altruistic tendencies (the more kinship cues, the more altruism). The same kinship cues, however, may have very, different effects within the context of mating, and the effects may also differ depending on whether individuals are considering long-term or short-term relationships. In the context of long-term relationships in which compatibility is of primary importance, individuals may tend to be attracted toward similar others, even i f that similarity simultaneously serves as a kinship cue. For short-term relationships, there may be a low threshold at which any addition of kinship cues reduces attractiveness. Clearly, the heuristic perception of kinship has wide-ranging implications. Many of these implications involve new ways of thinking about existing problems in social psychology, in areas such as altruism, attraction, and relationships. 7.2.2. Parasite-recognition mechanisms. Several questions surround parasiterecognition mechanisms as well. Studies described in this dissertation showed that the perception of individuals displaying parasite cues automatically activates disease-relevant concepts, which may represent functional cognitions of parasite-recognition mechanisms. But these studies also revealed that nonspecific negative cognitions are activated as well. Thus, it's not clear just how distinct the functional cognitions (e.g., disease concepts) and emotions (e.g., disgust) are from other kinds of negative cognitions and emotions. Perhaps the psychological responses involved in parasite recognition are not distinct from other negative responses for good reasons. There are many different kinds of dangerous people and things, and a common solution to many of these threats— outgroup members, harmful animals, parasite carriers—is physical avoidance. Thus, there may be some overlap among functional cognitions and emotions that motivate physical avoidance in the presence of different kinds of threats. A good example of a  Ill  common reaction to different threats is disgust. Not only is disgust involved in avoidance of parasite carriers, it is also involved in rejection of harmful food and rejection of kin as sexual partners (Fessler & Navarette, 2004; Rozin & Fallon, 1987). Disgust may have been further co-opted by other psychological mechanisms, such as those involved in moral judgments (Rozin, Lowery, Imada, & Haidt, 1999). If a common emotion plays a major role in these diverse processes, the notion of domain specificity—if conceptualized as one emotion for one problem—may be too simplistic. There is another important issue in the discussion of parasite-recognition mechanisms: Parasite recognition may take on added significance in the context of mating. There are several reasons for this. First, mating involves physical contact of the sort that is especially likely to transmit parasites (some parasites are exclusively transmitted by mating behaviors); thus, parasite cues may produce especially strong reactions in the context of mating. Second, mating usually produces offspring (at least that's the evolutionary function of mating), and as a result, individuals are discriminating when choosing partners. A great deal of evidence indicates that mate preferences that contributed to reproductive fitness have become panhuman adaptations (Buss & Schmitt, 1993). Parasite recognition is relevant to mate preferences, because (1) individuals carrying parasites are less likely to be healthy parents, and (2) the presence of parasites may suggest that individuals have lower heritable resistance to parasites, which will get passed on to offspring. Thus, not only are people likely to be repelled by parasite cues, they may be attracted to individuals who show signs of parasite resistance—individuals who appear physically attractive (see section 4.4). Accordingly, it's also possible that people may be especially motivated to conceal parasite cues in the context of mating— which isn't a big leap from the observation that people try hard to appear physically attractive in the context of mating (e.g., cosmetically covering up blemishes). A more  112 interesting hypothesis is that such motivation may be moderated by concerns about parasites or salience of parasites in the context. 7.2.3. Universality of evolved mechanisms. Many cue-recognition mechanisms may be evolved adaptations and thus panhuman; but they may manifest differently in different cultures because they necessarily depend on early experiences. How can we reconcile the evolutionary perspective (that emphasizes universality) and the cultural perspective (that emphasizes diversity)? With respect to cue recognition, there may be evolved constraints that influence how readily and robustly certain features are learned as cues. These evolved constraints may reflect circumstances in ancestral environments— specifically, the degrees of correlation between particular features and attributes. If the correlation between a particular cue and attribute was high, humans may have evolved to be prepared to learn that association especially quickly (e.g., snake-like shapes and danger). Such "reliable" cues may produce more powerful—and more culturally universal—responses. For instance, some kinship cues (e.g., early coresidence) may be more powerful, because they were more reliably correlated with actual kinship during evolutionary history. As a result, responses to such reliable kinship cues may be more culturally universal. On the other hand, the tendency to respond to less reliable kinship cues (e.g., attitude similarity) may be more culturally variable, because there are fewer evolved constraints. Similar logic applies to parasite cues. Some physical deviations (e.g., facial disfigurements) may have been reliably correlated with parasites (Thornhill & Gangestad, 1999), and as a result, aversive reactions to facial disfigurements may be robust and culturally universal. Other deviations may have been only weakly correlated with parasites—in fact, features such as extreme obesity may be evolutionarily novel. As a result, aversive reactions to such cues may be weaker and more culturally variable.  113 7.4. Conclusion Our daily life is filled with interactions with people. Without much control on our part, different thoughts and feelings are turned on and off by different individuals. Such reactions may be the product of distinct cue-recognition mechanisms that have been shaped by evolution. Because of these mechanisms, we may be attentive to cues that signal attributes such as kinship, the presence of parasites, group membership, and fertility. Examining our cue-recognition mechanisms may, therefore, help us attain a deeper understanding of our reactions to other people.  7.5. References Berscheid, E., Reis, H . T. (1998). Attraction and close relationships. In D. T. Gilbert, S. T. Fiske, & G. Lindzey (Eds.), The handbook of social psychology (4th ed., pp. 193— 281). New York: McGraw-Hill. Burnstein, E., Crandall, C., & Kitayama, S. (1994). Some neo-Darwinian decision rules for altruism: Weighing cues for inclusive fitness as a function of the biological importance of the decision. Journal of Personality and Social Psychology, 67, 773-789. Buss, D. M . , & Schmitt, D. P. (1993). Sexual strategies theory: A n evolutionary perspective on human mating. Psychological Review, 100, 204-232. DeBruine, L. M . (2005). Trustworthy but not lust-worthy: Context-specific effects of facial resemblance. Proceedings of the Royal Society of London B, 272, 919-922. Essock-Vitale, S. M . , & McGuire, M . T. (1985). Women's lives viewed from an evolutionary perspective. II. Patterns of Helping. Ethology and Sociobiology, 6, 155-173.  114 Fessler, D. M . T., & Navarrete, C. D. (2004). Third-party attitudes toward sibling incest: Evidence for Westermarck's hypotheses. Evolution and Human Behavior, 25, 277-294. Hamilton, W. D. (1964). The genetical evolution of social behaviour. Journal of Theoretical Biology, 7, 1—52. Keating, C. F., Randall, D. W., Kendrick, T., & Gutshall, K . A . (2003). Do babyfaced adults receive more help? The (cross-cultural) case of the lost resume. Journal of Nonverbal Behavior, 27, 89-109. Ohman, A., & Mineka, S. (2001). Fear, phobia, and preparedness: Toward an evolved module of fear and fear learning. Psychological Review, 108, 483-522. Rozin, P., & Fallon, A . E. (1987). A perspective on disgust. Psychological Review, 94, 23-41. Rozin, P., Lowery, L., Imada, S., & Haidt, J. (1999). The C A D triad hypothesis: A mapping between three moral emotions (contempt, anger, disgust) and three moral codes (community, autonomy, divinity). Journal of Personality and Social Psychology, 76, 574-586. Stewart, R. B. (1983). Sibling attachment relationships: Child-infant interactions in the strange situation. Developmental Psychology, 19, 192-199. Thornhill, R., & Gangestad, S. W. (1999). Facial attractiveness. Trends in Cognitive Sciences, 3, 452—460. Zebrowitz, L. A . (1997). Reading faces: Window to the soul? Boulder, CO: Westview Press.  115 Appendix A. Faith in Intuition Scale  Fl For each of the 12 statements below, indicate the extent to which you agree or disagree with the statement. Indicate your rating by circling a number between 1 and 5(1= completely false; 5 = completely true).  completely false 1. My initial impressions of people are almost always right. 2. I trust my initial feelings about people. 3. When it comes to trusting people, I can usually rely on my "gut feelings." 4.1 believe in trusting my hunches. 5.1 can usually feel when a person is right or wrong even if I can't explain how I know. 6.1 am a very intuitive person. 7.1 can typically sense right away when a person is lying. 8.1 am quick to form impressions about people. 9.1 believe I can judge character pretty well from a person's appearance. 10. I often have clear visual images of things. 11.1 have a very good sense of rhythm. 12.1 am good at visualizing things.  completely true  116 Appendix B. Attitudes Questionnaire (High Heritability)  Attitudes Questionnaire (H) Different people have different opinions regarding various issues and activities. Please take a moment to think about the issues and activities listed below. Then, please indicate how you feel about each item by circling a number. "My overall attitude toward [issue or activity] is" 1 (extremely  unfavorable)  to 6 (extremely  favorable)  extremely unfavorable 1. Death penalty for murder  2. Playing organized sports  3. Abortion on demand  4. Reading books  5. Roller coaster rides  extremely favorable  117 Appendix C. Attitudes Questionnaire (Low Heritability)  Attitudes Questionnaire (L) Different people have different opinions regarding various issues and activities. Please take a moment to think about the issues and activities listed below. Then, please indicate how you feel about each item by circling a number. "My overall attitude toward [issue or activity] is" 1 (extremely  unfavorable)  to 6 (extremely  favorable)  extremely favorable  extremely unfavorable 1. Separate roles for men and women  2. Loud music  3. Playing bingo  4. Easy access to birth control  5. Being assertive  2  3  118  Appendix D. Questions about Elaine and Carol  1. Recall that Elaine agrees with you on <ill of the above issues, and Carol disagrees with you on all of them. With that in mind, please indicate the extent to which you feel you could see things from Elaine and Care il's perspective: I could easily see things from her perspective  I could not see things from her perspective Elaine  1  2  3  4  5  6  Carol  1  2  3  4  5  6  2. If Elaine and Carol needed some assistance with school work because they could not attend lectures due to personal difficulties, how willing would you be to help them (for example, by taking notes for them)? I would not be willing to assist her  I would be very willing to assist her  Elaine  1  2  3  4  5  6  Carol  1  2  3  4  5  6  3. Behavioral geneticists have discovered that some attitudes are heritable. This means that two people who are highly similar on some attitudes also tend to share more genes with each other. Think about the attitudes that you share with Elaine and do not share with Carol. Based only on that information (ignoring physical similarity, gender, ethnic background), to what extent do you think you shares genes with Elaine and Carol? Think of 1 as someone completed unrelated to you, and 6 as someone who might be somewhat closely related to you (such as a cousin). I do not think she and I share a lot of our genes  i think she and I share a lot of our genes  Elaine  1  2  3  4  5  6  Carol  1  2  3  4  5  6  119 Appendix E. Perceived Vulnerability to Disease Scale  Health Beliefs Questionnaire Listed below are 19 statements. For each statement, rate the extent to which you agree or disagree with it. Indicate your rating by circling the number between 1 and 7 which best reflects your opinion (1 = strongly disagree, 7 = strongly agree). Strongly Agree  Strongly Disagree 1.1 am comfortable sharing a water bottle with a friend. 2.1 suffer quite intense symptoms when I do get sick. 3. It really bothers me when people sneeze without covering their mouths. 4.1 don't like to write with a pencil someone else has obviously chewed on. 5. My past experiences make me believe I am not likely to get sick even when my friends are sick. 6.1 prefer to wash my hands pretty soon after shaking someone's hand.  3  4  5  6  7  7.1 dislike wearing used clothes because you don't know what the last person who wore it was like.  3  4  5  6  7  8. If an illness is 'going around', I will get it.  3  4  5  6  7  9.1 don't worry about contamination if I touch an animal.  3  4  5  6  7  10. In general, I am very susceptible to colds, flu and other infectious diseases.  3  4  5  6 - 7  120 Strongly Disagree 11.1 think day care centers are breeding grounds for bacteria and germs.  1  12. Contagious diseases do not pose a particularly serious health risk for most people.  1  13.1 am more likely than the people around me to catch an infectious disease.  1  14. My hands do not feel dirty after touching money.  1  15.1 am unlikely to catch a cold, flu 1 or other illness, even i f it is going around. 16. It does not make me anxious to be around sick people.  1  17. M y immune system protects me from most illnesses that other people get.  1  18.1 avoid using public telephones because of the risk that I may catch something from the previous user.  1  19.1 have a history of susceptibility to infectious disease.  1  Strongly Agree  121  Appendix F. Belief in a Dangerous World Scale Beliefs About the World Questionnaire Below are 12 statements. For each statement below, rate the extent to which you agree or disagree with the statement. Indicate your rating by circling a number between 1 and 7 (1 = strongly disagree; 7 = strongly agree). strongly disagree 1. It seems that every year there are fewer and fewer truly respectable people, and more and more persons with no morals at all who threaten everyone else. 2. Although it may appear that things are constantly getting more dangerous and chaotic, it really isn't so. Every era has its problems, and a person's chances of living a safe, untroubled ,life are better today than ever before.  1  1  strongly agree 2  2  3  4  3  4  5  5  6  6  7  7  3. If our society keeps degenerating the way it has been lately, it's liable to collapse like a rotten log and everything will be in chaos.  1  2  3  4  5  6  7  4. Our society is not full of immoral and degenerate people who prey on decent people. News reports of such cases are grossly exaggerating and misleading.  1  2  3  4  5  6  7  5. The "end" is not near. People who think that earthquakes, wars and famines mean G o d might be about to destroy the world are being foolish.  1  2  3  4  5  6  7  6. There are many dangerous people in our society who will attack someone out of pure meanness, for no reason at all.  1  2  3  4  5  6  7  7. Despite what one hears about "crime in the street," there probably isn't any more now than there ever has been.  1  2  3  4  5  6  7  8. Any day now, chaos and anarchy could erupt around us. All the signs are pointing to it.  1  2  3  4  5  6  7  9. If a person takes a few sensible precautions, nothing bad will happen to him. W e do not live in a dangerous world.  1  2  3  4  5  6  7  10. Everyday, a s our society becomes more lawless and 1 bestial, a person's chances of being robbed, assaulted, and even murdered go up and up.  2  3  4  5  6  7  11. Things are getting so bad, even a decent law-abiding person who takes sensible precautions can still become a victim of violence and crime.  1  2  3  4  5  6  7  12. Our country is not falling apart or rotting from within.  1  2  3  4  5  6  7  v  1 2 2  Appendix G. Disgust Sensitivity Scale  Please indicate how much you agree with each of the following statements, or how true it is about you. Please write a number (1, 2,3 or 4) to indicate your answer: 1 = Strongly disagree (very untrue about me) 2 = Mildly disagree (somewhat untrue about me) 3 = Mildly agree (somewhat true about me) 4 = Strongly agree (very true about me) 1.1 might be willing to try eating monkey meat, under some circumstances. 2.1 try to avoid letting any part of my body touch the toilet seat in a public restroom, even when it appears clean. 3. It would bother me to be in a science class, and to see a human hand preserved in ajar. 4. It would make me uncomfortable to hear a couple making love in the next room of a hotel. 5. If I see someone vomit, it makes me sick to my stomach. 6.1 have no problem buying and wearing shirts from used clothing stores. 7. It would bother me tremendously to touch a dead body. 8. It would bother me to see photos of two people having oral sex. 9. Seeing a cockroach in someone else's house doesn't bother me. 10.1 probably would not go to my favorite restaurant if I found but that the cook had a cold. 11. It would bother me to sleep in a nice hotel room if I knew that a man had died of a heart attack in that room the night before. 12. It is OK with me if people want to look at pornography involving animals. 13. Even if I was hungry, I would not drink a bowl of my favorite soup if it had been stirred by a used but thoroughly washed fly-swatter. 14.1 would not hold a dollar bill between my lips (like if I needed a free hand), because so many strangers have touched it with their dirty hands. 15.1 find it disturbing to look at a person with lots of "body piercings" (like through the tongue and nose). 16.1 think that people who masturbate every day are degrading themselves.  How disgusting would you find each of the following experiences? Please write a number (1, 2, 3, or 4) to indicate your answer: 1 = Not disgusting at all, 2 = Slightly disgusting, 3 = Moderately disgusting, 4 = Very disgusting If you think something is bad or unpleasant, but not disgusting, you should write "1". 17. You see maggots on a piece of meat in an outdoor garbage pail. 18. You take a sip of soda and then realize that you picked up the wrong can, which a stranger had been drinking out of. 19. You see someone accidentally stick afishinghook through his finger. 20. You hear about a 30 year old man who seeks sexual relationships with 80 year old women. 21. While you are walking through a tunnel under a railroad track, you smell urine. 22. You sit down on a public bus, and feel that the seat is still warm from the last person who sat there. 23. You see a man with his intestines exposed after an accident. 24. As part of a sex education class, you are required to inflate a new unlubricated condom, using your mouth.  25. A friend offers you a piece of chocolate shaped like dog-doo. 26. You find out that someone you despise used to live in your house, and sleep in your bedroom. 27. Your friend's pet cat dies, and you have to pick up the dead body with your bare hands. 28. You hear about an adult brother and sister who like to have sex with each other. 29. You see a bowel movement left unflushed in a public toilet. 30. While traveling for 2 weeks with a friend, you discover that your underwear got mixed up in the wash, and you are wearing your friend's underwear. 31. You accidentally touch the ashes of a person who has been cremated. 32. While walking through a park, you see two dogs mating (having sex).  124 Appendix H . Sample Page of Questionnaire: Physical/Nonphysical Avoidance Note. Below is one page of the questionnaire (for one contact scenario). The same series of pictures and rating scales were repeated for the three remaining contact scenarios.  Social Knowledge Questionnaire We're investigating people's knowledge of how other people might feel in various social interactions with stigmatized individuals (for example, individuals who are obese or disabled). For this questionnaire, please try to guess how an average student at UBC might feel. For each target individual below, indicate the extent to which the average student might feel uncomfortable about interacting with the target individuals. Indicate your rating by circling a number between 1 and 10 1 = the average student would be very comfortable 10 = the average student would be very uncomfortable  125 1. How would an average student feel about shaking h a n d s with these individuals?  an obese man  very comfortable 1 2 3  4  5  6  7  8  very uncomfortable 9 10  4  5  6  7  8  very uncomfortable 9 10  a woman with HIV  very comfortable 1 2 3 a man with a criminal record  very uncomfortable 8 10  very comfortable 1 2 3 a man with an amputated leg  very comfortable 1 2 3  6  very uncomfortable 8 10  a man with a facial birthmark  very comfortable 1 2 •  very uncomfortable 8 10  126 Appendix I. Anti-Fat Attitudes Scale Attitudes Toward Eating and Dieting  For each of the 13 statements below, rate the extent to which you agree or disagree with the statement. Indicate your rating by circling a number between 1 and 10 (1 = strongly disagree; 10 = strongly agree). strongly disagree 1.1 worry about becoming fat.  strongly agree  1 2  3  4  5  6  4  5  6  7  8  2.1 feel disgusted with myself when I gain weight. 1  2 3  3. One of the worst things that could happen to me would be if I gained 25 pounds.  1  2  3  4  5  6  4. People who weigh too much could lose at least some part of their weight through a little exercise.  1  2  3  4  5  6  5. I don't have many friends that are fat.  1  6. Some people are fat because they have no willpower.  1  7. Although some fat people are surely smart, in general, I think they tend not to be quite as bright as normal weight people.  1 2 3 4 5 6 7 . 8  8.1 have a hard time taking fat people too seriously.  1  9. Fat people tend to be fat pretty much through their own fault.  1 2 3  10. Fat people make me feel somewhat uncomfortable.  1  11.1 tend to think that people who are overweight are a little untrustworthy.  1  12. If I were an employer looking to hire, I might avoid hiring a fat person. 13. I really don't like fat people much.  2  3  2  3  2  2  1  1  4  3  2  4  4  3  2  2  3  5  6  6  9  10  7  8  9  10  7  8  7  9  8  7  7  9 8  0  9  10  9  10  10  10  8  9  5  6  7  8  9  7  1  9  7  6  10  8  6  5  10  8  5  4  4  3  6  5  4  3  5  7  9  8  1  9  4  5  6  7  8  4  5  6  7  8  0  10  9  9  10  1  0  

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