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Effects of response habits on the performance of obese, average and fluctuator subjects Aves, Penelope Jill 1976

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EFFECTS OF RESPONSE HABITS ON THE PERFORMANCE OF OBESE, AVERAGE AND FLUCTUATOR SUBJECTS B.A., Northern I l l i n o i s U n i v e r s i t y , 1970 M.S., Purdue U n i v e r s i t y , 1972 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY i n THE FACULTY OF GRADUATE STUDIES Department of Psychology We accept t h i s t h e s i s as conforming by PENELOPE JILL AVES to the required standard THE UNIVERSITY OF BRITISH COLUMBIA JULY, 1976 Penelope J i l l Aves, 1976 In p r e s e n t i n g t h i s t h e s i s in p a r t i a l f u l f i l m e n t o f the r e q u i r e m e n t s f o r an advanced degree at the U n i v e r s i t y o f B r i t i s h C o l u m b i a , I a g r e e t h a t the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and s t u d y . I f u r t h e r agree t h a t p e r m i s s i o n f o r e x t e n s i v e c o p y i n g o f t h i s t h e s i s f o r s c h o l a r l y p u r p o s e s may be g r a n t e d by the Head o f my Department o r by h i s r e p r e s e n t a t i v e s . It i s u n d e r s t o o d that c o p y i n g o r p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l not be a l l o w e d w i t h o u t my w r i t t e n p e r m i s s i o n . Department o f \" SVCtKjU>k>Y The U n i v e r s i t y o f B r i t i s h C o l u m b i a 2075 Wesbrook P l a c e Vancouver, Canada V6T 1W5 Date ^ \C\1Q, ABSTRACT The purpose of t h i s study was to assess the r e l a t i v e influence of stimulus cues and response tendencies on the behavior of average and co n s i s t e n t l y or i n c o n s i s t e n t l y overweight i n d i v i d u a l s . The female undergraduate volunteers who p a r t i c i p a t e d i n the study were assigned to one of three weight groups on the basis of weight h i s t o r y , present weight, and t r i c e p s s k i n f o l d measurements. The three groups included c o n s i s t e n t l y average, c o n s i s t e n t l y overweight, and " f l u c t u a t o r " subjects. This l a s t group consisted of subjects whose weights over the past two years had varied between the average and overweight c l a s s i f i c a t i o n s . There were 20 subjects i n each of the three groups. A l l subjects completed two experimental tasks and were also administered the Eysenck Personality Inventory (EPI), Form A. The f i r s t experimental task, used previously by Sikes, involved guessing the colors (black or red) of 120 consecutively presented cards. Seventy-five per cent of the f i r s t 90 cards i n the seri e s were black, while a l l of the remaining 30 cards were red. As expected, there were no performance differences between groups on the f i r s t 90 cards; however, on the l a s t 30 cards co n s i s t e n t l y overweight p a r t i c i p a n t s made s i g n i f i c a n t l y more errors than ei t h e r average or f l u c t u a t o r subjects. This f i n d i n g i s consistent with Singh's d e f i c i t - i n - r e s p o n s e - i n h i b i t i o n hypothesis which maintains that overweight people have greater d i f f i c u l t y i n changing established response tendencies than do people of average weight. I t i s noteworthy, however, that i n the present study only people who had been c o n s i s t e n t l y overweight for the past i i i two years experienced more d i f f i c u l t y i n changing t h e i r e stablished responses. The second experimental task involved learning two paired associate word l i s t s i n an A-B/A-Br transfer paradigm. As expected, there were no performance differences between groups on the i n i t i a l l i s t . Contrary to expectations, however, there were also no d i f f e r -ences between groups on the transfer l i s t which required the suppressio of previously established responses. Thus, i n t h i s s i t u a t i o n consis-t e n t l y overweight subjects did not show the predicted d e f i c i t - i n -r e sponse-inhibition e f f e c t . The r e s u l t s , then, o f f e r p a r t i a l support f o r Singh's i n t e r p r e t a -t i o n of obesity i n terms of d i f f e r e n t i a l response tendencies. No support i s found f o r Schachter's i n t e r p r e t a t i o n which stresses the e f f e c t s of external cues, since obese subjects d i d not show performance that was superior to that of average subjects at any point. Results from analyses of subjects' scores on the EPI indicated that there were no differences between the three weight groups on either extraversion or neuroticism. In addition to providing some support for Singh's hypothesis, the experimental findings i n t h i s study indicate that i t i s important to consider recent weight h i s t o r y as well as present weight when inves-t i g a t i n g behavioral differences between overweight and normal i n d i v i d -uals. Implications of t h i s research for treatment of overweight i n d i v i d u a l s were discussed. i v TABLE OF CONTENTS Page ABSTRACT i i L I S T OF TABLES v i L I S T OF FIGURES v i i ACKNOWLEDGEMENT v i i i CHAPTER 1 : INTRODUCTION 1 E x p e r i m e n t a l F i n d i n g s 2 S u b c l a s s i f i c a t i o n s o f O b e s i t y 7 R a t i o n a l e o f t h e P r e s e n t I n v e s t i g a t i o n 11 O v e r v i e w o f E x p e r i m e n t 13 CHAPTER 2 : METHOD 17 S u b j e c t s 17 P e r s o n a l i t y M e a s u r e s 19 P h y s i c a l M e a s u r e s 19 M a t e r i a l s 19 P r o c e d u r e 21 CHAPTER 3 : RESULTS 24 S u b j e c t G r o u p i n g s 24 E x p e c t a n c y Change T a s k 24 P a i r e d A s s o c i a t e L e a r n i n g 26 E y s e n c k P e r s o n a l i t y I n v e n t o r y 30 C o r r e l a t i o n s be tween Degree o f O b e s i t y and E x p e r i m e n t a l M e a s u r e s 39 We igh t H i s t o r y 42 CHAPTER 4 : DISCUSSION 46 E x p e c t a n c y Change 46 P a i r e d A s s o c i a t e s 48 E x t r a v e r s i o n and N e u r o t i c i s m 49 G e n e r a l D i s c u s s i o n 51 I m p l i c a t i o n s f o r T r e a t m e n t 53 F u t u r e D i r e c t i o n s 55 REFERENCES 57 APPENDICES .61 A p p e n d i x A : I n i t i a l We igh t Q u e s t i o n n a i r e A p p e n d i x B : E x p e r i m e n t a l C o n s e n t Form 61 62 Page Appendix C: I n i t i a l and Transfer Lists used in Paired Associate Task 63 Appendix D: Instructions for the First List of the Paired Associate Task 64 Appendix E: Instructions for the Transfer List of the Paired Associate Task 65 Appendix F: Weight History and Medical Information Questionnaire 66 Appendix G: Summary of Results Mailed to Experimental Participants 68 v i LIST OF TABLES Table I. Table I I . Means and standard deviations of subject c h a r a c t e r i s t i c s by weight c l a s s i f i c a t i o n s Means and standard deviations of expectancy change measures by weight c l a s s i f i c a t i o n Page 20 25 Table I I I . Means and standard deviations of paired associate learning measures by weight c l a s s i f i c a t i o n s 29 Table IV. Means and standard deviations of extraversion, neuroticism, and l i e scale scores 31 Table V. Means arid standard deviations of expectancy change measures f or i n t r o v e r t s and extraverts 33 Table VI. Means and standard deviations of paired associate learning measures f o r i n t r o v e r t s and extraverts 34 Table VII. Means and standard deviations of expectancy change measures f o r normals and neurotics 36 Table VIII. Means and standard deviations of paired associate learning measures f o r normals and neurotics 37 Table IX. Means and standard deviations of extraversion and neuroticism scores by personality c l a s s i f i c a t i o n s 38 Table X. Means and standard deviations of expectancy change measures by personality c l a s s i f i c a t i o n s 40 Table XI. Means and standard deviations of paired associate learning measures by personality c l a s s i f i c a t i o n s 41 Table XII. Correlations between dependent measures f o r t r a n s f e r - o f - t r a i n i n g tasks and t r i c e p s s k i n f o l d by weight c l a s s i f i c a t i o n s 43 Table XIII. Analyses of group proportions f o r h i s t o r y of overweight during various l i f e periods 44 LIST OF FIGURES Number of errors in last 30 t r i a l s expectancy change task by weight classification v i i i ACKNOWLEDGEMENT I would like to express my appreciation to my committee chairman, Dr. Jerry Wiggins, for his advice and encouragement throughout this investigation. I also wish to thank Drs. Park Davidson, Boris Gorzalka, and Nancy Schwartz for consenting to serve on my committee and for suggestions concerning my research. Special assistance with the data analysis was provided by Virginia Green. I would also like to thank Dr. G.J. Johnson for his help with paired associate learning procedures. 1 CHAPTER 1 INTRODUCTION Overweight has become a problem of great concern in industrial-ized nations where a large proportion of the population i s well-fed but quite sedentary. Ponderal index values, calculated from height and weight, were obtained for a strati f i e d national sample of more than 19,000 Canadians as part of a national nutrition survey (Nutrition Canada, 1973). These figures indicated that more than half of the adult population (over 20 years of age) in Canada is overweight. In a 1966 survey of a st r a t i f i e d sample of the population of the United States by the Elmo Roper Company, 42% of the females and 36% of the males sampled f e l t that they were over their best weight (Dwyer & Mayer, 1970). Preoccupation with overweight among a large segment of the population can also be deduced from the number of popular books and articles dealing with diets, the proliferation of low-calorie food products and beverages, and the number of commercial reducing estab-lishments throughout the western world. Medical specialists are i n -creasingly warning the population of the health hazards of overweight. Even such an established tradition as l a grande cuisine in France is feeling the effects of increasing weight-consciousness. Michel Guerard, an outstanding French chef, has recently developed a novel approach termed l a cuisine minceur (Wechsberg, 1975). Derived from the French word mince, meaning "slim", this revolutionary approach attempts to provide high-quality gastronomic fare prepared with low-calorie, low-cholesterol ingredients. In view of the concern with overweight from many sources, the 2 proliferation of research on this topic i s not surprising. Programs aimed at producing weight loss i n obese patients have met, u n t i l recently, with uniformly dismal results. In 1958, the conclusion from a Cornell Conference on Obesity was that "most obese patients w i l l not remain in treatment. Of those who do remain in treatment, most w i l l not lose significant poundage, and of those who do lose weight, most w i l l regain i t promptly" (p. 87). With the advent of behavioral tech-niques of psychotherapy some programs have met with greater success (e.g., Harris, 1969; Stuart, 1967; Wollersheim, 1970). The main prob-lems with treatments presently involve obtaining c l i n i c a l l y significant rather than s t a t i s t i c a l l y significant weight losses in patients and finding methods of maintaining the desired weight once i t has been achieved. Experimental Findings The remarkable recidivism of the overweight has prompted some investigators to look for behavioral differences between obese and nor-mal persons in situations both relevant and irrelevant to eating behav-ior. Studies by Schachter and others have shown that the eating behav-ior of obese subjects is more affected by external cues such as taste (Nisbett, 1968), v i s i b i l i t y of food (Johnson, 1974), and time of day (Schachter & Gross, 1968) than the eating behavior of normal subjects. Other investigators have shown that overweight subjects respond more to environmental cues than normal subjects in situations quite unrelated to eating behavior, e.g., r e c a l l of items viewed on slides (Rodin, Herman, & Schachter, 1974) and proof-reading with and without distrac-tion (Rodin, 1973). Recently this stimulus-binding theory has been qualified somewhat in that obese individuals are assumed to be more 3 responsive than normal subjects to highly salient or potent cues in the environment while they are less responsive to weak or minimal cues. Pliner (1973), for instance, found an interaction between body weight and cue salience of auditory signals in a time estimation task. This finding illustrates the importance of considering the salience of external cues when investigating differences in environmental respon-siveness between overweight and normal subjects. Despite the considerable body of data in support of the hypothe-sis that the obese are especially susceptible to external cues, some researchers are dissatisfied with this explanation for the behavioral differences observed between obese and normal subjects. Singh (1973) has proposed a deficit-in-response-inhibition hypothesis to account for the findings and maintains that the behavior of overweight sub-jects i s mainly controlled by response tendencies. He states that "stimulus-bound behavior i n obese subjects would be evident only i n those situations where external cues and response tendencies are compatible. If cues and response tendencies are incompatible as exem-p l i f i e d by negative transfer of training or reversal-learning situa-tions, the behavior of obese subjects would be controlled by existing response tendencies" (p. 221). By constructing experimental situa-tions which necessitated changing dominant response patterns, Singh has repeatedly demonstrated a deficit-in-response-inhibition effect among obese subjects. In one experiment (Singh, 1973) obese and normal subjects received i n i t i a l training that was either compatible or incompatible with the subsequent experimental response required to obtain food. When training was compatible with the experimental 4 response, obese subjects ate slightly but not significantly more food than normal subjects; however, under the incompatible training condi-tion obese subjects consumed significantly less food than normals. Singh (1973) also showed that obese subjects performed worse than normals on a time estimation task when previous interfering training was given, and displayed greater problem-solving r i g i d i t y than normals when a mental set was created. In another experiment along the lines of a well-known Schachter investigation, Singh and Sikes (1974) offered obese and normal subjects chocolates and cashews, both being either wrapped or unwrapped. Schachter and Friedman (Schachter, 1971) had provided either shelled or unshelled almonds to subjects and had found that obese subjects ate more of the unshelled and less of the shelled almonds than normals who ate about the same amount of both. They concluded that obese subjects were less willing to work for food than normals. In Singh's study, neither subject weight nor wrapping had an effect upon chocolate comsumption, but in the case of cashews the obese subjects ate less of the wrapped than unwrapped nuts while there was no difference for the normals. In this situation, past experience seemed to be the important variable determining willingness to work for food. Sikes (1974) carried out a series of experiments in which predic-tions from the stimulus-binding and deficit-in-response-inhibition theories differed. Results from three of the four experiments were consistent with the deficit-in-response-inhibition hypothesis. In the f i r s t experiment, obese subjects were more resistant than normal subjects to an attitude change manipulation of strongly held attitudes. 5 The second experiment required participants to predict the colors of black and red cards in a stack. Overweight subjects had greater d i f f i c u l t y than normals in changing their expectations when the color feedback went from 75% black to 100% red. When subjects were required to perform a well-learned motor task in a different fashion, obese subjects did worse than normal subjects. It was only in the discrim-ination reversal experiment that the deficit-in-response-inhibition hypothesis was not supported because the obese subjects did not show the expected reversal effect while the; normal subjects did. Sikes's conclusion from these results was that the deficit-in-response-inhibi-tion theory is a better predictor of obese behavior than the stimulus-binding theory across a variety of situations. Efforts have been made by Singh and his associates to eliminate a number of alternative hypotheses which might account for the behavioral differences found between obese and normal subjects. Possible factors which might contribute to behavioral differences include intelligence, compliance, self-esteem, and motivation. Sikes (1974) found no differences between obese and normal subjects in intellectual a b i l i t y as measured by the vocabulary subtest of the Wechsler Adult I n t e l l i -gence Scale. In another experiment, results from measures of self-exteem, compliance, and motivation indicated there were no differences between obese and normal subjects (Sikes & Singh, 1974). Thus, i t appears that no alternative explanation has yet been found for the deficit-in-response-inhibition effect displayed by obese subjects in various contexts. The deficit-in-response-inhibition hypothesis provides an explana-tion for some of the known facts about obese behavior which have 6 presented problems for the stimulus-binding approach. For example, i f external cues determine eating behavior, why do the obese stop eating before a l l the food within sight has been consumed? Schachter (1971) has stated that the difference between obese and normal eating behavior appears to be due to the size of meals rather than the num-ber of meals. This observation can be explained by the d e f i c i t - i n -response- inhibition view since obese subjects are seen as having prob-lems with terminating an ongoing response; thus, they would be expected to continue responding longer than normal subjects, e.g., continuing to eat longer at meals, but not expected to consume a l l food within sight or to eat more meals than normal subjects. It must be pointed out that the predictions derived from the external cues and response inhibition hypotheses are not incompatible in many cases. Singh (1973) has pointed out that both can account for many of the observed behavioral differences between obese and normal subjects. Continued investigation of situations in which opposite predictions can be derived from these two viewpoints would seem war-ranted in order to specify classes of situations where one or the other might be more applicable. An important difference between these two lines of research involves the classification of experimental subjects. Schachter and his associates generally use the 1959 Metropolitan Life Insurance Company norms for ideal weight and classify subjects according to the percentage of deviation from the average weight for a given height. Subjects up to 10% above the average weight are classified as normal while those above 15% of the average weight are considered obese. 7 Though students participating in body^eontact sports are eliminated, there are s t i l l problems including differences in body frame and clothing. Singh uses the triceps skinfold thickness to classify sub-jects as obese since this measure reflects excess fatness rather than weight above average and is not influenced by body frame or height (Seltzer & Mayer, 1965). Correlations reported between these two indices of overweight are somewhat variable: .52 for females and .72 for males (Singh, 1973); .81 for males and females (Sikes, 1974). Therefore, i t would seem that researchers in this area should make use of skinfold measures in addition to weight deviations to ensure that experimental participants are both consistently and accurately assigned to their appropriate weight classifications. Such a methodological refinement would also f a c i l i t a t e comparisons of findings from various investigations of obesity. Subclassifications of Obesity One problem with most of the research investigating differences between obese and normal subjects involves the rather a r t i f i c i a l dichotomy employed. A United States Public Health Services report (1966) states that "obesity, the result of a positive caloric balance, can be the outcome of a number of disturbances. The variations in causes and subsequent manifestations indicate that not a l l obesity can be considered the same. For this reason, some investigators have come to use the plural term 'obesities' rather than obesity" (p. 33). Despite such statements most studies have looked at differences between one obese and one normal group. The exceptions to this rule have pro-vided interesting and occasionally conflicting results. In a 8 treatment setting involving obese patients with adult onset of the problem, Grinker, Hirsch, and Levin (1973) found l i t t l e adverse reac-tion to weight reduction, e.g., anxiety or depression, though previous research with patients having a history of juvenile onset indicated a number of negative reactions to weight loss. In another comparison of juvenile versus adult onset of obesity, Grinker, Glucksman, Hirsch, & Viseltaer (1973) found that subjects with juvenile onset underesti-mated time intervals after weight reduction, but this was not true of adult onset or normal subjects. Sikes (1974) divided her obese subjects into subgroups determined by age of onset (before or after age 10), evidence of traumatic exper-ience prior to weight gain, and substantial weight loss at some point in time which was subsequently regained. No differences, however, were found between the subgroups on any of the experimental measures. In a study involving obese and normal g i r l s at an Eastern U.S. college, Decke, Gold and Porikos (Schachter & Rodin, 1974) found that their results depended on the degree of obesity of the subjects. In an immediate recall task, moderately obese g i r l s (16%-48% overweight) did better than normals while the highly obese (53.3%-97.7% overweight) did worse than the normals. Nisbett (1972) reported that obese sub-jects who were 40% or more overweight behaved similarly to normal sub-jects in terms of amount of good and bad-tasting ice cream consumed, while obese subjects who were 15%-40% overweight were more responsive to taste and ate more of the good-tasting and less of the bad-tasting ice cream than either the normal or the substantially obese group. In another experiment investigating degree of obesity, Rodin (1975) found 9 that moderately obese subjects (15%-40% overweight) were significantly more influenced by their taste preferences for milkshakes in terms of food ingestion and food ratings than were average and obese (60% or more overweight) subjects. Another interesting classification of obesity involves the consis-tency with which one maintains a particular weight. Johnson (1974) used weight deviations from the 1959 Metropolitan Life Insurance tables to classify his subjects as obese versus normal. Only those subjects who reported weights over the past two years consistent with their present classification were used in the experiment. In another study, Rodin (1975) divided subjects within three weight c l a s s i f i c a -tions (average, moderately overweight, obese) on the basis of s t a b i l i t y of weight and eating patterns over the past two years in order to determine closeness to biological set point.^ Subjects were classified as below set point i f their weights had fluctuated by more than 7% in the past two years and they reported some dietary restrictions. If their weights had fluctuated no more than 3% with no dietary re s t r i c -tions and they weighed as much as they ever had, subjects were consid-ered to be at their set point. Weight stability had no significant effect on either food preference ratings or food intake when minimal effort was required; however, when more effort was required to obtain food, subjects below set point were more deterred than those at set Biological set point is a theoretical notion referring to an individ-ual organism's optimal state of adipose tissue mass. The biological set point is a function of the number of adipocytes or fat cells in the body, this number being determined by heredity and early nutri-tional experience and therefore not subject to change in adult l i f e (Cabanac, Duclaux, & Spector, 1971; Nisbett, 1972). 10 point. Though these r e s u l t s are i n t e r e s t i n g i n r e l a t i o n to the b i o l o g -i c a l set point hypothesis, the data presented do not i n d i c a t e whether any of the subjects c l a s s i f i e d as below set point had s u f f i c i e n t weight ranges over the past two years to span two or more of the weight c l a s -s i f i c a t i o n s used by Rodin. I f some of the subjects i n the below set point group had varied between the weight categories, i t would be i n t e r e s t i n g to know how these subjects responded on the experimental measures. Two studies by Schachter and h i s associates (Nisbett, 1968; Schachter, 1971) have also attempted to look at subjects with inc o n s i s -tent weight c l a s s i f i c a t i o n s according to weight h i s t o r y but they employed only post hoc analyses. In Nisbett's (1968) experiment with good and bad-tasting i c e cream, weight records indicated than 37% of the normal subjects had been overweight i n the past but were of normal weight at the time of the experiment. These "formerly f a t " subjects exhibited greater responsiveness to taste than the normals with no h i s t o r y of overweight and behaved s i m i l a r l y to the obese i n t h i s respect. Nisbett (1972) has more recently a t t r i b u t e d the obese-like behavior of these previously overweight subjects to the fa c t that they are below the biologically-programmed preferred weight or set point and behave l i k e the obese, i . e . , as i f they were hungry. In the Schachter and Friedman (Schachter, 1971) study with shelled and unshelled almonds, those normals who had been overweight behaved as the obese did, eating the shelled but not the unshelled nuts. One i n v e s t i g a t i o n has produced r e s u l t s contrary to t h i s notion of the "formerly f a t " behaving l i k e the obese (Price & Grinker, 1973). 11 Obese subjects from the obesity research program at Rockefeller University Hospital were c l a s s i f i e d on the basis of degree of obesity and age of onset ( j u v e n i l e , adolescent, and a d u l t ) . These obese subjects ate more than normal volunteers from the community i n both the preload and cracker-tasting conditions and were more responsive to t h e i r taste preferences than normals. No differences were found between the obese subgroups as a function of degree of obesity or age of onset i n terms of amount eaten or responsiveness to taste p r e f e r -ences. Within the normal group, 43% of the subjects reported some p r i o r h i s t o r y of overweight. The "formerly f a t " i n t h i s study behaved as the normals with no h i s t o r y of overweight both i n terms of the amount eaten and taste preferences. Rationale of the Present Investigation In view of the above r e s u l t s , research i n v e s t i g a t i n g " f l u c t u a t o r s " , or subjects whose recent weight h i s t o r y and present status i n d i c a t e some degree of v a c i l l a t i o n between obese and normal c l a s s i f i c a t i o n s , as an independent group might shed some l i g h t on the seemingly contradic-tory r e s u l t s of previous studies. Individuals with h i s t o r i e s of widely varying body weights constitute a group well-worth i n v e s t i g a t i n g f o r a number of further reasons. As stated e a r l i e r , a large proportion of the North American population seems to be concerned with i t s weight probably f o r both aesthetic and medical reasons. The mass media presen-tati o n s of i d e a l p h y s i c a l specimens are i n v a r i a b l y slim. Medical consultants are i n c r e a s i n g l y focusing on overweight as a major contrib-uting f a c t o r i n heart disease and other ph y s i c a l problems. The high v i s i b i l i t y of the diet industry indicates that a s u b s t a n t i a l number of 12 people are attempting to do something about their weight. A 1966 survey in the United States indicated that only 54% of the men and 30% of the women sampled ate whatever they wanted with no concern over gaining weight (Dwyer & Mayer, 1970). Within this same group, 6% of the males and 14% of the females sampled said they were presently on a diet while an additional 7% of the men and 13% of the women said that they dieted from time to time. Wyden (1965) stated that the average American goes on 1.25 diets a year with the average length of these being 60-90 days. The popularity of diets varies with the time of year, the most common being post-Christmas season and prior to summer. These facts create a picture of a substantial portion of society engaging in a continual battle with overweight, i.e., losing by dieting and/or exercising, regaining, and beginning again. The seriousness of this problem in terms of medical consequences is indicated by a U.S. Public Health Service report (1966) which states: Serum cholesterol levels are elevated during periods of weight gain, thus increasing the risk of deposition. There is no evidence to show that once cholesterol i s deposited i t can be removed by weight reduction. It is possible that a patient whose weight has fluctuated up and down a number of times has been subjected to more atherogenic stress than a patient with stable though excessive weight (p. 71). Stuart and Davis (1972) have expressed concern with these observa-tions and stated that weight reduction programs should be aimed at obtaining a stable weight which can be maintained over time. The prevalence of on-and-off dieting within North American society indicates that investigations which include a group of fluctuators along with obese and normal groups might provide interesting results in terms of hypotheses previously advanced about overweight individuals 13 and contribute some information which could be incorporated into thera-peutic procedures aimed at producing weight loss in various types of individuals. Since the negative transfer-of-training tasks ut i l i z e d by Singh in his research provide a test of the predictions of both the external cue and response inhibition hypotheses, the u t i l i z a t i o n of this type of task with normal, obese, and "fluctuator" subjects could provide data on the merits of these two hypotheses using a more differentiated classification of obesity. Also, tasks of this sort have not been employed with obese subgroups differing in weight st a b i l i t y to determine whether differential responses might be obtained in these situations. Overview of Experiment Obese, normal, and fluctuator subjects were asked to perform two transfer-of-training tasks. To allow a comparison of results between the present study and previous research based on the deficit-in-response-inhibition hypothesis, the black and red card color expectancy task designed by Pervin (1960) and i n i t i a l l y employed with obese subjects by Sikes (1974) was used in the present investigation. This task measures the extent to which subjects are able to modify their expectations according to the feedback they receive. Subjects were asked to guess the colors of 120 consecutive cards in a stack with participants viewing each card after every guess. The f i r s t 90 cards were 75% black, while the last 30 were a l l red. On the basis of previous research i t was hypothesized that obese subjects would have more d i f f i c u l t y in changing their i n i t i a l expectations than normal subjects. It was also hypothe-sized that fluctuator subjects, would have less d i f f i c u l t y in making the change than the consistently obese, but more d i f f i c u l t y than the 14 consistently average participants. The second transfer-of-training task involved paired associate learning. Subjects were trained to a specified criterion on an i n i t i a l l i s t and then asked to learn a second l i s t . The second l i s t was made up of the same words as the original l i s t , but the response words had been randomly assigned to different stimulus words thus creating an interference effect from the previous training. Paired associate learn-ing tasks have not been used previously with overweight and normal subjects though the paradigm involved in paired associate learning of a negative transfer l i s t would seem to be an ideal situation for comparing the predictions of the stimulus-binding and deficit-in-response-inhibi-tion theories. If overweight subjects are more responsive to external cues than normal subjects, the obese participants should perform better on both l i s t s of the paired associates task than the normal subjects. If, on the other hand, the differential performance of overweight and normal subjects is due to response tendencies as Singh (1973) has pro-posed, then the obese and normal subjects should differ mainly in performance on the second or transfer l i s t because performance on this l i s t would require suppressing established responses to the stimulus words. Results of the majority of investigations involving negative transfer-of-training situations have provided support for the d e f i c i t -in-response-inhibition theory. On the basis of this body of research i t was hypothesized that consistently overweight subjects would perform more poorly than consistently average subjects on the second l i s t in the paired associate learning task. It was also hypothesized that fluctuating subjects or those with highly variable weight histories 15 would perform better than the obese subjects on the second l i s t but worse than the average subjects. There i s a p o t e n t i a l a l t e r n a t i v e explanation a v a i l a b l e f o r the pre-dicted differences between obese, normal, and f l u c t u a t o r subjects on the paired associates learning task. A recent review (M.W. Eysenck, 1976) has summarized the findings of numerous experimental i n v e s t i g a -tions on the r e l a t i o n s h i p between the personality dimensions of extra-version and neuroticism and performance on a v a r i e t y of verbal learning and memory tasks. A number of studies (Allsopp & Eysenck, 1974; Bone, 1971; Howarth, 1969) have shown that the learning performance of extra-verts i s superior to that of i n t r o v e r t s on paired associate l i s t s which are highly competitive. A recent i n v e s t i g a t i o n by M.W. Eysenck (1975) allowed subjects a longer period for responding than i s conven-t i o n a l l y used i n paired associate tasks. No differences were found i n terms of correct responses between groups varying along the dimensions of extraversion and neuroticism, but i n d i v i d u a l differences were rela t e d to response latency. Eysenck concluded from these findings that extraverts are not better learners but rather f a s t e r r e t r i e v e r s of information than i n t r o v e r t s . Regardless of the s p e c i f i c explanation for the differences i n performance between extraverts and i n t r o v e r t s on paired associate tasks with b r i e f periods allowed f o r responding, i t would seem appro-p r i a t e to include a measure of extraversion within the present inves-t i g a t i o n to determine whether obese, normal, and f l u c t u a t o r subjects d i f f e r along t h i s dimension. Results from one study (Taylor, 1971) indicated a s i g n i f i c a n t c o r r e l a t i o n between the i n t r o v e r s i o n f a c t o r and small amount of lean body mass i n black, male, college-age 16 students. The Eysenck Personality Inventory (Eysenck & Eysenck, 1968) was administered to a l l subjects i n t h i s i n v e s t i g a t i o n . This inventory provides scores on both the neuroticism and extraversion dimensions as w e l l as a l i e scale to c o n t r o l f o r the response set of s o c i a l d e s i r a b i l i t y . 17 CHAPTER 2 METHOD Subjects Volunteer subjects were obtained from 42 undergraduate classes i n psychology, education, and n u t r i t i o n . Female students who were i n t e r -ested i n p a r t i c i p a t i n g i n an experiment concerning the r e l a t i o n s h i p between body b u i l d , behavior, and personality were asked to complete an i n i t i a l questionnaire (Appendix A) on weight h i s t o r y over the past two years. P o t e n t i a l volunteers indicated t h e i r highest and lowest weights over the past two years as w e l l as t h e i r present weights. The weight h i s t o r y information was used to s e l e c t subjects i n i t i a l l y as f l u c t u a t o r s , c o n s i s t e n t l y normal, or c o n s i s t e n t l y obese according to a standard table of Canadian heights and weights (Pett & O g i l v i e , 1956). During the experimental appointment, height, weight, and t r i c e p s s k i n f o l d measures were taken, and these figures were used for the f i n a l subject c l a s s i f i -cations. P a r t i c i p a n t s were c l a s s i f i e d as normal i f t h e i r t r i c e p s skin-f o l d measures were between the tenth and s i x t i e t h c e n t i l e s of a standard d i s t r i b u t i o n of s k i n f o l d measures for females (U.S. Dept. of Health, Education, & Welfare, 1970) and also t h e i r present weight and weight h i s t o r y data indicated a c o n s i s t e n t l y normal c l a s s i f i c a t i o n (within 10% of the tabled average weight for a given height (Pett & O g i l v i e , 1956)). Subjects were c l a s s i f i e d as obese i f t h e i r t r i c e p s s k i n f o l d measures were above the e i g h t i e t h c e n t i l e of a standard d i s t r i b u t i o n of s k i n f o l d measures for females and also t h e i r present weights and weight h i s t o r y data indicated a co n s i s t e n t l y obese c l a s s i f i c a t i o n (15% or more above 18 the tabled average weight f or a given height). P a r t i c i p a n t s were c l a s s i f i e d as fl u c t u a t o r s i f t h e i r weights over the past two years had varied s u b s t a n t i a l l y enough that t h e i r highest weights were at le a s t 15% above t h e i r lowest weights and t h e i r lowest weights were within the normal c l a s s i f i c a t i o n while t h e i r highest weights were within the obese c l a s s i f i c a t i o n . No r e s t r i c t i o n s were placed on the s k i n f o l d 2 measure f o r the fl u c t u a t o r group. To ensure that subject groups were homogeneous with respect to other p o t e n t i a l l y important v a r i a b l e s , two general r e s t r i c t i o n s were placed upon p a r t i c i p a t i o n i n the experiment. Only p o t e n t i a l volunteers between 18-25 years of age were contacted f or p a r t i c i p a t i o n i n the study. Secondly, subjects whose fl u c t u a t i o n s i n weight were a r e s u l t of pregnancy, l a c t a t i o n , or serious i l l n e s s were not included i n the study. This information was obtained from the i n i t i a l questionnaire and the experimental consent form (Appendix B). Sixty subjects p a r t i c i p a t e d i n the experiment. Twenty subjects were obtained from the sample of p o t e n t i a l volunteers who agreed to p a r t i c i p a t e i n the experiment and who met the requirements of the consi s t e n t l y overweight c l a s s i f i c a t i o n . To maintain equal numbers of subjects i n the three weight groups, twenty subjects were also obtained f o r both the f l u c t u a t o r and normal groups. Descriptive 2 The f l u c t u a t o r group included both i n d i v i d u a l s who were overweight and i n d i v i d u a l s who were within the normal weight range at the time of the experiment. Weight and s k i n f o l d measurements taken on subjects within the f l u c t u a t o r group indicated that nine subjects were obese and s i x subjects were normal at the time of the experi-ment while f i v e of the subjects did not f i t ei t h e r c l a s s i f i c a t i o n as t h e i r weights and/or s k i n f o l d measurements were above the normal range but below the obese range used i n the experiment. 19 s t a t i s t i c s on age, height, weight, and t r i c e p s s k i n f o l d f or these three groups are shown i n Table I. Personality Measures The Eysenck Personality Inventory was administered to a l l p a r t i -cipants. This 57-item s e l f - r e p o r t inventory provides scores on extra-version and neuroticism as well as a l i e scale. Form A of the inven-tory was used becuase t h i s version contains no items d i r e c t l y relevant to eating habits or food preferences. Physical Measures Triceps s k i n f o l d measurements were obtained with a Lange Skinfold Caliper. Subjects were weighed on a portable household scale which had been adjusted with reference to a standard medical balance scale. Height measurements were obtained on a wall chart. A l l subjects were weighed and measured i n indoor clothing and without shoes. Materials One hundred and twenty standard playing cards, not including face cards, were used for the expectancy change task. The f i r s t 90 cards were randomly presented but consisted i n t o t a l of 75% black and 25% red cards, and the l a s t 30 cards were a l l red. For the paired associate task two l i s t s of 12 pairs of two-s y l l a b l e adjectives were constructed with adjectives taken from Melton (1940) .and Haagen (1949). Subjects were randomly assigned within groups to learn one of the two i n i t i a l l i s t s . The second l i s t for each subject was constructed from items i n her i n i t i a l l i s t using a A-B, A-Br t r a n s f e r paradigm. To construct the second l i s t s , the s t i m u l i and responses from the i n i t i a l l i s t s were randomly re-paired. Table I Means and Standard Deviations 3 of Subject Characteristics by Weight Classifications Weight (pounds) Percent Overweight Triceps Skinfold (mm.) Height (inches) Age Average 130.90 -.59 13.75 64.85 19.95 (n=20) (11.28) (3.23) (2.24) (2.78) (1.85) Fluctuator 151.40 16.34 21.55 64.50 19.75 (n=20) (20.61) (15.05) (5.19) (2.61) (1.65) Obese 170.55 29.60 28.10 64.78 19.80 (n=20) (28.38) (16.80) (2.79) (2.84) (1.88) aStandard deviations in parentheses 21 Items were selected to minimize the e f f e c t s of s t r u c t u r a l and meaning-f u l s i m i l a r i t y both within and across the l i s t s . The l i s t s were pre-sented on a memory drum at a 2:2 rate with four seconds between t r i a l s . To minimize s e r i a l learning e f f e c t s , four d i f f e r e n t random orders of the 12 pair s i n each l i s t were used. I n i t i a l and transfe r l i s t s may be found i n Appendix C. Procedure Subjects were chosen on the basis of i n i t i a l questionnaire data and contacted by telephone to arrange experimental appointments. Four of the subjects contacted no longer wished to p a r t i c i p a t e or f a i l e d to keep t h e i r appointments. Upon a r r i v a l at the laboratory p a r t i c i p a n t s were asked to sign an experimental consent form. Then each subject p a r t i c i p a t e d i n the two tasks inv o l v i n g the re v e r s a l of established response tendencies and completed the Eysenck Personality Inventory (EPI). The order of the two tra n s f e r tasks was counterbalanced within each subject c l a s s i f i c a t i o n . When a subject had f i n i s h e d the f i r s t task she was asked to complete the EPI. Following the completion of t h i s scale the second task was administered. One of the tasks involved changing expectancies of card colors which was previously used by Sikes (1974). The procedure and i n s t r u c -tions given here are i d e n t i c a l to those used i n her experiment. The subject and experimenter were seated at a table with a stack of playing cards between them. The experimenter sai d , "I have here a stack of cards, which I w i l l turn over one at a time. Before I turn over each card, I would l i k e f o r you to guess whether i t w i l l be red or black. What color do you think the f i r s t card w i l l be?" The subject made a 22 guess, and the experimenter turned the card over to show her the correct color. The experimenter then put the card on the table, recorded her response, and asked, "What color do you think this card w i l l be?" This procedure was followed for a l l 120 cards. As stated earlier the f i r s t 90 cards were 75% black and 25% red while the last 30 cards were a l l red. . When the color proportion changed no indication was given to the subject that this had occurred. The second task involved learning two l i s t s of paired associates. The subject was seated in front of a memory drum with the experimenter seated behind her coding the subject's responses. Instructions were given for the f i r s t l i s t (Appendix D) and training on the f i r s t l i s t began. Each subject was given a maximum of 25 anticipation t r i a l s on the f i r s t l i s t . Training on the f i r s t l i s t ended when the subject achieved two perfect recitations of the f i r s t l i s t or when she had received 26 presentations of the l i s t , whichever occurred f i r s t . After a rest interval of approximately two minutes the subject was given the instructions for the transfer l i s t (Appendix E). Then the subject was given ten anticipation t r i a l s (not including the f i r s t presentation) on the transfer l i s t . After each subject had completed her second transfer-of-training task, she was asked to f i l l out a f i n a l questionnaire containing items relating to weight history, diet restrictions, and medical information which might be relevant to weight (Appendix F). Finally, weight, height, and triceps skinfold measurements were taken on each subject. At the end of the experiment, subjects were given a brief explanation of the experimental hypotheses and procedures; a ful l e r statement, which included the results and conclusions of the experi ment was mailed to subjects at their home addresses at a later date approximately four months after they had participated (Appendix G). CHAPTER 3 RESULTS Subject Groupings There were s i g n i f i c a n t differences between the three weight groups on the weight (F(2,57)=17.38, p<.01), percent overweight CF(2,57)=26.46, p<v01) and t r i c e p s s k i n f o l d (_F(2,57)=77 .97, p<.01) measures. Compari-sons between a l l pairs of means of the three groups on these measures were made using the Tukey "a" procedure (Winer, 1962, p. 87). A l l contrasts between mean pair s were s i g n i f i c a n t f o r the three measures (weight, percent overweight, and t r i c e p s skinfold) at the .05 l e v e l . Subject groups did not d i f f e r s i g n i f i c a n t l y on e i t h e r height (F< 1) or age (_F< 1) . The means and standard deviations are shown i n Table I (Chapter 2). Expectancy Change Task Subjects i n the three weight c l a s s i f i c a t i o n groups were i n i t i a l l y compared on the number of incorrect responses they made i n the f i r s t 90 t r i a l s of the expectancy change task when the cards were 75% black and 25% red. A one-way analysis of variance indicated that there were no s i g n i f i c a n t differences between average, f l u c t u a t o r , and obese sub-j e c t s i n terms of the number of errors made i n the f i r s t 90 cards (F(2,57)< 1). The means and standard deviations on the measures used i n the expectancy change task are shown i n Table I I . The numbers of incorrect responses made by subjects i n the three weight groups on t r i a l s 76-90 were also compared to determine whether there were any differences between groups immediately p r i o r to the change i n the card r a t i o i n the stack from 75% black and 25% red to a l l Table II Means and Standard Deviations 3 of Expectancy Change Measures by Weight Classification Errors Errors Errors Trials 1-90 Trials 76-90 Trials 91-120 Average 39.05 5.90 4.05 (n=20) (6.36) (1.71) (2.28) Fluctuator 38.50 6.65 4.05 (n=20) (4.05) (1.18) (1.57) Obese 39.05 6.25 5.85 (n=20) (4.30) (1.62) (2.87) aStandard deviations in parentheses 26 red. Results indicated that there were no s i g n i f i c a n t differences between the average, f l u c t u a t o r , and obese groups i n terms of the num-ber of errors made i n t r i a l s 76-90 (F(2,57)=1.22, n.s.). The number of errors made by subjects i n the three weight groups on t r i a l s 91-120 when a l l the cards were red was the c r i t i c a l measure on the expectancy change task. Results from a one-way analysis of variance indicated that there was a s i g n i f i c a n t difference between groups on the number of errors made i n t r i a l s 91-120 (F_(2,57)=4.07, p<.05). To inves-t i g a t e the source of t h i s difference comparisons were made between the group means using the Tukey "a" procedure (Winer, 1962, p. 87). The number of errors made by the obese group was s i g n i f i c a n t l y greater than the number of errors made by both the f l u c t u a t o r and the average groups (p<.05). The fl u c t u a t o r group did not d i f f e r s i g n i f i c a n t l y from the average group on number of errors i n cards 91-120. The number of errors made by the three weight groups on the l a s t 30 cards wass:-. also analysed i n blocks of ten t r i a l s to investigate the p o s s i b i l i t y of a d i f f e r e n t i a l d i s t r i b u t i o n of errors between the groups over t r i a l s . Results from a 3 X 3 between-within analysis of variance indicated s i g n i f i c a n t e f f e c t s both for weight group (F(2,57)=4.07, p<.05) and t r i a l s (F2,114)=106.15, p<.01), but the i n t e r -action between weight groups and t r i a l s was not s i g n i f i c a n t (_F(4,114)=1.23, n.s.). Figure 1 i l l u s t r a t e s the t o t a l number of errors made by subjects i n the three weight groups on the l a s t 30 t r i a l s by blocks of ten t r i a l s . Paired Associate Learning Subjects i n the three weight groups were compared on two measures 27 Figure 1. Number of errors in Last 30 Trials of Expectancy Change Task by Weight Classification 28 of f i r s t l i s t learning to determine whether the groups d i f f e r e d i n performance on the paired associate task without response interference. Results from an analysis of the number of t r i a l s necessary f o r achieving the learning c r i t e r i o n f o r the f i r s t l i s t indicated there were no s i g n i f i c a n t differences between the three weight groups on t r i a l s to c r i t e r i o n (F_ <1) . There was an approximately equal number of subjects within each of the three weight groups who did not achieve two consecutive perfect r e c i t a t i o n s of the l i s t i n the a l l o t t e d 25 a n t i c i -pation t r i a l s . T r i a l scores of 26 were assigned to those subjects (6 average, 5 f l u c t u a t o r s , and 5 obese) who had not achieved the l e a r n -ing c r i t e r i o n for the f i r s t l i s t . The number of i n t r a l i s t i ntrusions (responses contained i n the l i s t but given to the wrong stimulu) given by subjects i n the three weight groups on the f i r s t l i s t were also compared. No s i g n i f i c a n t difference was found between groups on the number of i n t r a l i s t i n t r u s i o n s (F < 1) . The means and standard deviations f o r a l l of the dependent measures on the paired^associate learning task are shown i n Table I I I . Measures of learning on the second or tr a n s f e r l i s t where response competition was high were compared across the three weight c l a s s i f i c a -t i o n groups f o r the f i r s t t r i a l and for a l l ten t r i a l s . There was no s i g n i f i c a n t difference between groups on the t o t a l number of errors made i n T r i a l 1 (F<1). There were also no s i g n i f i c a n t differences between groups on ei t h e r the number of i n t r a l i s t i ntrusions (F_< 1) or the number of i n t e r l i s t i ntrusions (responses which were correct on the f i r s t l i s t ) made i n T r i a l 1 of the tra n s f e r l i s t (F_<1). Results from an analysis of the t o t a l number of errors made by Table III Means and Standard Deviations 3 of Paired Associate Learning Measures by Weight Classifications First List Transfer List T r i a l 1 Trials 1-10 Trials to Intralist Total Intralist Interlist Total Intralist Interlist Criterion Intrusions Errors Intrusions Intrusions Errors Intrusions Intrusions Average 18.90 21.90 9.95 1.15 .25 60.60 12.55 6.10 (n=20) (6.58) (20.08) (1.54) (1.46) (.55) (22.87) (9.22) (5.08) Fluctuator 17.65 21.20 9.20 1.35 .40 62.45 12.75 8.35 (n=20) (7.94) (22.78) (2.31) (1.31) (.60) (24.97) (10.00) (5.31) Obese 19.30 19.95 9.55 1.20 .45 64.00 12.80 7.15 (n=20) (4.77) (21.57) (1.67) (1.24) (.60) (24.91) (12.45) (3.88) Standard deviations in parentheses 30 subjects i n the three weight groups on a l l 10 t r i a l s of the t r a n s f e r l i s t indicated that there were no s i g n i f i c a n t group differences on the t o t a l number of errors (F<1). There were also no s i g n i f i c a n t d i f f e r -ences between groups on ei t h e r the number of i n t r a l i s t i n t r u s i o n s (F<1) or the number of i n t e r l i s t i n t r u s i o n s (F_(2,57)=1.10, n.s.) made over a l l 10 t r i a l s of the t r a n s f e r l i s t . Eysenck Personality Inventory Subjects' scores on the extraversion and neuroticism scales of the EPI were compared across the three weight groups. There was no s i g n i f -icant d i f f e r e n c e between groups on the extraversion measure (F(2,57)=1.50, n.s.). There was also no s i g n i f i c a n t d i f f e r e n c e between groups on the neuroticism measure (F < 1) . Results from an analysis of scores on the l i e scale of the EPI indicated there was no s i g n i f i c a n t difference between the groups on t h i s measure (F<1). Table IV shows the means and standard deviations of extraversion, neuroticism, and l i e scale scores f or the three weight groups. The r e l a t i o n s h i p of extraversion and neuroticism to performance on the two experimental tasks was investigated independently of weight c l a s s i f i c a t i o n s . High and low-scoring subjects on the extraversion scale (upper and lower 27% of the d i s t r i b u t i o n of extraversion scores) were compared on each of the dependent measures f o r the two experimen-t a l tasks. The mean scores on the extraversion scale f o r high and low scorers (extraverts and i n t r o v e r t s ) were, re s p e c t i v e l y , 17.00 and 8.44. On the expectancy change task, there were no s i g n i f i c a n t differences between extraverts and i n t r o v e r t s on the number of errors made i n the 31 Table IV Means and Standard Deviations 3 of Extraversion, Neuroticism, and Lie Scale Scores Extraversion Neuroticism Lie Average 12.45 11.10 2.35 (n=20) (3.12) (5.26) (1.23) Fluctuator 11.95 12.15 2.45 (n=20) (3.75) (4.13) (1.47) Obese 13.85 11.35 2.85 (n=20) (3.87) (3.44) (2.25) aStandard deviations in parentheses 32 f i r s t 90 t r i a l s (_F(1,30)=1.05, n.s.), the number of errors made i n t r i a l s 76-90 (F(1,30)=1.31, n.s.), or the number of errors made i n the l a s t 30 t r i a l s ( F < 1 ) . The means and standard deviations of scores on the expectancy change task f o r i n t r o v e r t s and extraverts are l i s t e d i n Table V. On the f i r s t l i s t of the paired associate task there were no s i g n i f i c a n t differences between i n t r o v e r t s and extraverts on eit h e r the number of t r i a l s to c r i t e r i o n (F_<1) or the number of i n t r a l i s t i n t r u s i o n s ( F < 1 ) . The means and standard deviations of scores on the paired associate learning measures for i n t r o v e r t s and extraverts are shown i n Table VI. On the f i r s t t r i a l of the transf e r l i s t there were no s i g n i f i c a n t differences between the groups on the t o t a l number of errors ( F < 1 ) , the number of i n t r a l i s t i ntrusions (_F<1), or the number of i n t e r l i s t i ntrusions (jF <1). For a l l ten t r i a l s of the tra n s f e r l i s t there were no s i g n i f i c a n t differences between i n t r o v e r t s and extraverts on the t o t a l number of errors (F_<1), the number of i n t r a l i s t intrusions ( F < 1 ) , or the number of i n t e r l i s t i ntrusions (F <1) made i n t r i a l s 1-10. High and low-scoring subjects on the neuroticism scale (upper and lower 27% of the d i s t r i b u t i o n of neuroticism scores) were also compared on each of the dependent measures f o r the two experimental tasks. The mean scores on the neuroticism scale f o r high and low scorers (neurotics and normals) were, re s p e c t i v e l y , 17.00 and 6.38. On the expectancy change task there were no s i g n i f i c a n t differences between neurotics and normals on the number of errors made i n the f i r s t 90 t r i a l s ( F < 1 ) , the number of errors made i n t r i a l s 76-90 (J_<1), or 33 Table V Means and Standard Deviations of Expectancy Change Measures fo r Introverts and Extraverts Errors T r i a l s 1-90 Errors T r i a l s 76-90 Errors T r i a l s 91-120 Introverts (n=16) Extraverts (n=16) 37.50 (5.40) 39.44 (5.30) 6.44 (1.90) 5.75 (1.48) 5.06 (2.77) 4.88 (2.31) Standard deviations i n parentheses Table VI Means and Standard Deviations 3 of Paired Associate Learning Measures for Introverts and Extraverts First List Transfer List T r i a l 1 Trials 1-10 Trials to Intralist Total Intralist Interlist Total Intralist Interlist Criterion Intrusions Errors Intrusions Intrusions Errors Intrusions Intrusions Introverts 17.81 19.75 9.44 .88 .38 58.19 10.31 6.69 (n=16) (7.93) (16.38) (2.25) (1.36) (.62) (27.67) (9.69) (4.22) Extraverts 18.88 20.13 9.44 1.06 .31 63.13 9.81 6.31 (n=16) (6.39) (24.44) (2.03) (1.12) (.60) (23.96) (7.06) (4.09) aStandard deviations in parentheses 35 the number of errors made i n the l a s t 30 t r i a l s (F(l,30)=2.60, n.s.). The means and standard deviations of scores on the expectancy change task f o r normals and neurotics are l i s t e d i n Table VII. On the f i r s t l i s t of the paired associate learning task there were no s i g n i f i c a n t differences between groups on either the number of t r i a l s to c r i t e r i o n (F(l,30)=1.40, n.s.) or the number of i n t r a l i s t i ntrusions (F(l,30)=4.09, p=.052) though the l a t t e r d i f f e r e n c e j u s t f e l l short of the conventionally accepted l e v e l of s i g n i f i c a n c e . The means and standard deviations of scores on the paired associate l e a r n -ing task f o r normals and neurotics are shown i n Table VIII. On the f i r s t t r i a l of the tr a n s f e r l i s t there were no s i g n i f i c a n t differences between normals and neurotics on the t o t a l number of errors (F <1) , the number of i n t r a l i s t intrusions (F <1), or the number of i n t e r l i s t i n trusions (F(l,30)=1.36, n.s.). For a l l ten t r i a l s of the transf e r l i s t there were no s i g n i f i c a n t differences between groups on the t o t a l number of errors (F <1), the number of i n t r a l i s t i ntrusions (F(l,30)=2.07, n.s.), or the number of i n t e r l i s t i n t r u s i o n s (F <1) . Subjects were also divided into groups on the basis of t h e i r scores on both the extraversion and the neuroticism scales. Four groups of subjects ( n e u r o t i c - i n t r o v e r t s , neurotic-extraverts, normal-i n t r o v e r t s , normal-extraverts) were formed by constructing a scatter p l o t of the b i v a r i a t e d i s t r i b u t i o n of extraversion and neuroticism and l o c a t i n g c l u s t e r s of subjects f a l l i n g i n the four quadrants. Cut-of f scores that best equalized the number of subjects i n the four groups were determined and used to form the four personality groups. Table IX l i s t s the means and standard deviations of scores on the Table VII Means and Standard Deviations 3 of Expectancy Change Measures for Normals and Neurotics Errors Trials 1-90 Errors Trials 76-90 Errors Trials 91-120 Normals 38.75 (3.61) 5.94 (1.24) 4.19 (2.29) Neurotics 39.50 (4.35) 6.38 (1.50) 5.56 (2.53) Standard deviations in parentheses Table VIII Means and Standard Deviations 3 of Paired Associate Learning Measures for Normals and Neurotics First List Transfer List T r i a l 1 Trials 1-10 Trials to Intralist Total Intralist Interlist Total Intralist Interlist Criterion Intrusions Errors Intrusions Intrusions Errors Intrusions Intrusions Normals 20.25 30.13 9.75 1.06 .38 65.06 16.50 6.50 (n=16) (6.34) (29.28) (1.98) (1.18) (.50) (28.07) (13.71) (4.05) Neurotics 17.75 14.06 9.63 .88 .19 60.38 10.50 7.19 (n=16) (5.60) (12.29) (1.71) (1.45) (.40) (20.09) (9.51) (5.46) aStandard deviations in parentheses Table IX Means and Standard D e v i a t i o n s 3 of Extraversion and Neuroticism Scores by Personality C l a s s i f i c a t i o n s Extraversion Neuroticism Normal-Introverts 9.23 7.69 (n=13) (2.98) (2.98) Normal-Extraverts 15.47 8.74 (n=19) (2.06) (2.07) Neurotic-Introverts 10.38 15.88 (n=16) (1.93) (3.07) Neurotic-Extraverts 15.42 14.33 (n=12) (2.31) (1.50) Standard deviations i n parentheses 39 extraversion and neuroticism scales for these four groups. The four personality groups were compared on a l l of the experimen-t a l measures for the two learning tasks. On the expectancy change task there were no s i g n i f i c a n t differences between the four personality groups on the number of errors made i n the f i r s t 90 t r i a l s (F <1), the number of errors made i n t r i a l s 76-90 CF <1), or the number of errors made i n the l a s t 30 t r i a l s (F(3,56)=1.07, n.s.). The means and stan-dard deviations of scores on the expectancy change task for the four personality groups are l i s t e d i n Table X. On the f i r s t l i s t of the paired associate learning task there were no s i g n i f i c a n t differences between the personality groups on either the number of t r i a l s to c r i t e r i o n (F <1) or the number of i n t r a -l i s t i n t r u s i o n s (F(3,56)=1.89, n.s.). Table XI shows the means and standard deviations of scores on the paired associate learning task f o r the four personality groups. On the f i r s t t r i a l of the t r a n s f e r l i s t there were no s i g n i f i c a n t differences between the four personality groups on the t o t a l number of errors (F_ <1) , the number of i n t r a l i s t i n trusions (F(3,56)=1.50, n.s.), or the number of i n t e r l i s t i ntrusions (F<1). For a l l ten t r i a l s of the t r a n s f e r l i s t there were no s i g n i f -icant differences between groups on the t o t a l number of errors (F<1), the number of i n t r a l i s t i ntrusions (F<1), or the number of i n t e r l i s t i n t r u s i o n s (_F(3,56)=1.13, n.s.). Correlations between Degree of Obesity and Experimental Measures Because the f l u c t u a t o r group included both overweight and average weight i n d i v i d u a l s based on measurements taken at the time of the experiment, there might be some question whether present weight 40 Table X, Means and Standard Deviations 3 of Expectancy Change Measures by Personality Classification Errors Trials 1-90 Errors Trials 76-90 Errors Trials 91-120 Normal- 37.62 6.24 4.46 Introverts (n=13) (5.09) (1.69) (2.50) Normal- 38.90 6.22 4.21 Extraverts (n=19) (4.84) (1.51) (2.55) Neurotic- 38.94 6.57 5.56 Introverts (n=16) (5.47) (1.36) (2.73) Neurotic- 40.09 6.00 4.33 Extraverts (n=12) (4.42) (1.71) (1.44) aStandard deviations in parentheses Table XI Means and Standard D e v i a t i o n s 3 of Paired Associate Learning Measures by Personality C l a s s i f i c a t i o n s F i r s t L i s t Transfer L i s t T r i a l 1 T r i a l s 1-10 T r i a l s to I n t r a l i s t Total I n t r a l i s t I n t e r l i s t T o t a l I n t r a l i s t I n t e r l i s t C r i t e r i o n Intrusions Errors Intrusions Intrusions Errors Intrusions Intrusions Normal-Introverts (n=13) 19.15 (7.02) 29.46 (28.74) 9.61 (2.53) 1.23 (1.30) .54 (.78) 63.31 (27.19) 15.62 (14.50) 7.38 (5.03) Normal-Extraverts (n=19) 19.74 (6.40) 24.32 (22.54) 9.47 (1.93) 1.68 (1.34) .42 (.51) 65.37 (24.08) 14.05 (10.11) 8.47 (5.14) Neurotic-Introverts (n=16) 17.19 (6.88) 17.31 (17.24) 9.56 (1.46) .75 (1.44) .25 (.45) 57.13 (22.49) 9.56 (8.41) 7.00 (4.59) Neurotic-Extraverts (n=12) 18.17 (5.88) 11.58 (6.49) 9.67 (1.61) 1.17 (1.03) .25 (.62) 63.50 (23.65) 11.58 (8.10) 5.25 (4.18) Standard deviations i n parentheses 42 c l a s s i f i c a t i o n s were related to the dependent measures regardless of weight h i s t o r y . To investigate t h i s p o s s i b i l i t y , product-moment co r r e l a t i o n s were computed between t r i c e p s s k i n f o l d measures of sub-j e c t s i n the f l u c t u a t o r group and scores on each of the dependent mea-sures for the two t r a n s f e r - o f - t r a i n i n g tasks. The t r i c e p s s k i n f o l d measure was used as an i n d i c a t i o n of degree of obesity because of i t s r e l a t i v e lack of dependence upon body b u i l d and height and because the tr i c e p s s k i n f o l d measure was highly correlated with percent overweight across a l l subjects i n the present i n v e s t i g a t i o n (r=.84, p<.001). The number of errors made by fl u c t u a t o r subjects i n the f i r s t 90 t r i a l s of the expectancy change task was the only dependent measure s i g n i f i c a n t l y r e l a t e d to the magnitude of the t r i c e p s s k i n f o l d measure (r=-.43, p<.05). Since a large number of co r r e l a t i o n s were obtained and there were no s i g n i f i c a n t differences between the three weight groups on the number of errors made i n the f i r s t 90 t r i a l s i t i s quite possible that the c o r r e l a t i o n was due to chance. Correlations were also computed between the t r i c e p s s k i n f o l d measure and scores on each of the dependent measures f o r subjects i n the average and obese weight groups. For subjects i n the cons i s t e n t l y overweight group the degree of obesity as measured by the t r i c e p s s k i n f o l d was s i g n i f i c a n t l y r e l a t e d to f i v e of the experimental measures. The co r r e l a t i o n s between the t r i c e p s s k i n f o l d and scores on each of the dependent measures f o r a l l three weight groups are shown i n Table XII. Weight History Subjects were asked to in d i c a t e whether or not they had been over-weight during a number of periods i n t h e i r l i v e s . Table XIII shows Table XII Correlations between Dependent Measures for Transfer-of-Training Tasks and Triceps Skinfold by Weight C l a s s i f i c a t i o n s Average Fluctuator Obese Expectancy Change Task Errors i n T r i a l s 1-90 -.025 -.433* .254 Errors i n T r i a l s 76-90 -.048 -.121 .157 Errors i n T r i a l s 91-120 .198 -.075 .383* Paired Associate Task  F i r s t L i s t T r i a l s to C r i t e r i o n -.123 .186 .504* I n t r a l i s t Intrusions -.125 .058 .664** Transfer L i s t ( T r i a l 1) Total Errors -.080 .342 .123 I n t r a l i s t Intrusions -.148 .242 .694** I n t e r l i s t Intrusions .011 .214 .159 Transfer L i s t ( T r i a l s 1-10) To t a l E r r o r s -.158 .151 .422* I n t r a l i s t Intrusions -.324 .256 .376 I n t e r l i s t Intrusions -.423* .229 .363 * * S i g n i f i c a n t at .01 l e v e l * S i g n i f i c a n t at .05 l e v e l Table XIII Analyses of Group Proportions for History of Overweight During Various L i f e Periods Proportion Overweight Overall L i f e Periods Average Fluctuator Obese X (df = 2) S i g n i f i c a n t M u l t i p l e Comparisons Childhood Pre-Teens Adolescence Adulthood .05 .05 .45 .20 Cumulative (at l e a s t once) .55 .25 .40 .90 .90 1.00 .45 .60 .85 1.00 1.00 12.465 25.846 12.507 36.190 21.176 <.005 <.001 <.005 <.001 <.001 Average vs. Obese Average vs. Fluctuator Average vs. Obese Average vs. Fluctuator Average vs. Obese Average vs. Fluctautor Average vs. Obese Average vs. Fluctuator Average vs. Obese This o v e r a l l ^ i s the test s t a t i s t i c associated with the test of several independent proportions (see Marascuilo, 1966). A l l multiple comparisons were conducted with an experimentwise alpha l e v e l of .05. 45 the proportion of subjects i n each of the three weight groups who indic a t e d that they had been overweight i n various l i f e periods and also shows the r e s u l t s from analyses performed on these data. As can be seen i n Table XIII, the average group d i f f e r e d from the obese group i n terms of h i s t o r y of overweight f o r a l l of the l i f e periods sampled. The f l u c t u a t o r group d i f f e r e d from the average group on overweight h i s t o r y for a l l l i f e periods except that of childhood. 46 CHAPTER 4 DISCUSSION Expectancy Change The r e s u l t s obtained i n the expectancy change task were quite consistent with the predictions made concerning the behavior of obese and normal subjects from the d e f i c i t - i n - r e s p o n s e - i n h i b i t i o n theory. There were no differences between subjects i n the three weight groups on the f i r s t part of the task which i s consistent with Singh's theory because subjects were not required to change a dominant response pattern. The f a c t that there were no differences between groups on the i n i t i a l part of the task; however, indicates that the obese subjects i n t h i s case were not more s e n s i t i v e to the external cues provided by the color feedback as would have been expected from the stimulus-binding viewpoint. The s i g n i f i c a n t difference found between groups on the second part of the task, where subjects received d i f f e r e n t color feedback and had to change t h e i r previous expectancies, provides support f o r the d e f i c i t - i n - r e s p o n s e - i n h i b i t i o n theory. Group compari-sons indicated that the cons i s t e n t l y obese subjects made s i g n i f i c a n t l y more errors i n the second phase of the task than both the f l u c t u a t o r subjects and the co n s i s t e n t l y average subjects. Moreover, most of the errors made by subjects i n a l l three weight groups occurred during the f i r s t ten t r i a l s (see Figure 1, Chapter 3). This indicates that most subjects did change t h e i r expectancies during the second phase of the task, but the obese subjects took longer to do so than e i t h e r the average or the f l u c t u a t o r subjects. The r e s u l t s from the expectancy change task i n t h i s i n v e s t i g a t i o n 47 are consistent with those of Sikes (1974). However, i n her i n v e s t i g a -t i o n only the obese and normal subjects who had made 66% or more correct responses i n the l a s t 15 cards of the i n i t i a l part of the task d i f f e r e d on the second part of the task. This difference between high-performing obese and normal subjects was s i g n i f i c a n t on the f i r s t seven t r i a l s a f t e r the color r a t i o had changed. The r e s u l t s from the present i n v e s t i g a t i o n provide a p o t e n t i a l explanation f o r the lack of an o v e r a l l s i g n i f i c a n t difference between obese and normal subjects i n Sikes's experiment. In the present study only the obese group which was made up of subjects who had been c o n s i s t e n t l y overweight for the past two years displayed the d e f i c i t - i n - r e s p o n s e - i n h i b i t i o n e f f e c t . Though a l l subjects i n the f l u c t u a t o r group were ei t h e r overweight at the present time or had been overweight at some point during the past two years, these subjects did not d i f f e r from the normal subjects on the expec-tancy change task. It has been suggested that overweight people con-s t i t u t e a heterogeneous group, and i t i s quite possible that consis-t e n t l y overweight people behave d i f f e r e n t l y from people whose recent weights have varied between the average and overweight c l a s s i f i c a t i o n s . Since Sikes did not d i f f e r e n t i a t e between obese subjects on the basis of recent weight h i s t o r y , her obese group was probably more hetero-geneous than that employed i n the present study and might have included a number of f l u c t u a t o r subjects who did not display a d e f i c i t - i n - r e s p o n s e - i n h i b i t i o n e f f e c t . More research involving groups of obese i n d i v i d u a l s d i f f e r i n g i n recent weight h i s t o r y i s needed to determine whether f l u c t u a t o r and obese subjects d i f f e r on other tasks and i n other s i t u a t i o n s . It should also be noted that 48 Sikes's sample contained both males and females whereas only females p a r t i c i p a t e d i n the present study. However, since no sex differences have been reported i n previous investigations involving both male and female subjects (Singh, 1973; Singh & Sikes, 1974), t h i s difference i n sampling i s probably of minor importance compared to the d i f f e r e n c e i n c l a s s i f i c a t i o n of obese subjects on the basis of weight h i s t o r y . Since the f l u c t u a t o r group contained both obese and normal i n d i -v iduals according to measurements taken at the time of the experiment, there might be some question whether present weight c l a s s i f i c a t i o n s were rel a t e d to performance on the second part of the expectancy change task. The nonsignificant c o r r e l a t i o n between the t r i c e p s s k i n -f o l d measure and the number of errors on the l a s t 30 cards indicated that t h i s was not the case. Also, the mean number of errors for pres-ently obese (3.77) and average i n d i v i d u a l s (4.27) within the f l u c t u a t o r group were quite s i m i l a r implying that weight h i s t o r y was the important f a c t o r i n determining f l u c t u a t o r s ' responses and not present c l a s s i f i -cations. In summary, the r e s u l t s on the expectancy change task support the d e f i c i t - i n - r e s p o n s e - i n h i b i t i o n hypothesis but i n d i c a t e that only the c o n s i s t e n t l y obese subjects have greater d i f f i c u l t y i n changing an established response on t h i s task. No support was found f o r the s e n s i t i v i t y to external cues hypothesis. Paired Associates On the second experimental task which involved paired associate learning there were no differences between the three weight groups on any of the experimental measures. This task had been constructed as a 49 t e s t of the d e f i c i t - i n - r e s p o n s e - i n h i b i t i o n theory with performance on the second l i s t r equiring subjects to suppress responses which had been established during the learning of the i n i t i a l l i s t . Because no differences were found between the weight groups on any of the measures of second l i s t learning, these r e s u l t s provide no support for the view that obese subjects w i l l have greater d i f f i c u l t y i n overcoming estab-l i s h e d response tendencies. Since no differences were obtained between the weight groups on measures of f i r s t l i s t learning, the present r e s u l t s also do not support the stimulus-binding theory. I f obese subjects were more responsive to the external cues i n t h i s task, they should have learned the i n i t i a l l i s t more quickly than the average subj ects. The lack of any s i g n i f i c a n t differences between groups and the extremely large v a r i a b i l i t y within groups on the paired associate task suggest that other factors are more important than weight i n determin-ing performance i n t h i s s i t u a t i o n , I t i s possible that some combina-t i o n of factors including memory, information processing, cognitive s t y l e , and imagery and i n t e l l e c t u a l a b i l i t y determine performance on tasks of t h i s sort and that subject differences on these f a c t o r s obscure any d i f f e r e n t i a l performance r e s u l t i n g from weight c l a s s i f i -cations or weight h i s t o r y . Regardless of the explanation f or the lack of differences between weight groups on t h i s task, the present findings do not support the p o s i t i o n that obese i n d i v i d u a l s display a generalized d e f i c i t - i n - r e s p o n s e - i n h i b i t i o n i n comparison to average i n d i v i d u a l s , Extraversion and Neuroticism There were no s i g n i f i c a n t differences between the three weight 50 groups on the personality dimensions of extraversion and neuroticism as measured by the EPI. The reason f o r the administration of the EPI i n the present study was to determine whether subjects d i f f e r e d along ei t h e r the extraversion dimension or the neuroticism dimension. Results from a number of previous studies have indicated that scores on these two dimensions, e s p e c i a l l y the extraversion scale, were rel a t e d to performance on verbal learning and memory tasks. The EPI was used i n the present experiment to determine whether an a l t e r n a t i v e explana-t i o n based on personality differences could be advanced to account f o r any differences found between the three weight groups on the experimen-t a l measures. The lack of a s i g n i f i c a n t difference between groups on either personality dimension indicated that the s i g n i f i c a n t difference between groups on the expectancy change task was not a r e s u l t of a. p r i o r i differences between groups on extraversion and/or neuroticism. This f i n d i n g also detracts from a possible a l t e r n a t i v e explanation based on personality differences for differences reported between obese and normal subjects i n previous i n v e s t i g a t i o n s . Since r e s u l t s from a number of e a r l i e r i n v e s t i g a t i o n s had i n d i -cated that scores on the EPI were r e l a t e d to performance on verbal learning and memory tasks, the r e l a t i o n s h i p of extraversion and neuroticism to performance on the two experimental tasks used i n the present study was investigated independently of weight c l a s s i f i c a t i o n . There were no s i g n i f i c a n t differences between i n t r o v e r t s and extraverts or between neurotics and normals on any of the experimental measures for either the expectancy change task or the paired associate learning task. S i m i l a r l y , when subjects were divided i n t o four personality 51 groups (normal-introverts, normal-extraverts, n e u r o t i c - i n t r o v e r t s , neurotic-extraverts) there were again no s i g n i f i c a n t differences between the groups on any of the performance measures f or the two experimental tasks. The lack of s i g n i f i c a n t differences between person-a l i t y groups on the transfer l i s t of the paired associate task i s somewhat inconsistent with r e s u l t s from e a r l i e r studies which have found differences between personality groups on s i m i l a r tasks involving competitive word l i s t s , e.g., Allsopp and Eysenck (1974), Bone (1971), and Howarth, (1969). However, the fact that the sample used i n the present i n v e s t i g a t i o n was not random since subjects were selected on the basis of recent weight h i s t o r y may account f o r these discrepancies. General Discussion The experimental findings i n the present i n v e s t i g a t i o n provide some support f o r the d e f i c i t - i n - r e s p o n s e - i n h i b i t i o n theory based on the r e s u l t s of the expectancy change task but indic a t e that obese subjects i n future research should be c l a s s i f i e d on the basis of recent weight h i s t o r y and consistency of the overweight condition. Self-report data were obtained for a l l subjects concerning the periods of t h e i r l i v e s when they had been overweight. There were s i g n i f i c a n t differences between the three weight groups f o r a l l four l i f e periods sampled i n d i c a t i n g that weight differences between the three groups extended much further than the two-year period used f o r experimental c l a s s i f i c a t i o n of subjects. Further speculation based on these data would probably be inappropriate because subjects were not asked to give any i n d i c a t i o n of the degree of overweight and also subjects' responses on these items were based on self-perceptions of overweight 52 which are often quite d i f f e r e n t from an objective assessment based on normative data. Subjects were also asked to i n d i c a t e i f they were presently on a d i e t . Subjects r e s t r i c t i n g t h e i r food intake might be viewed as hungry and possibly below t h e i r b i o l o g i c a l set points. If more obese than f l u c t u a t o r subjects were presently d i e t i n g , t h i s d i f f e r -ence between groups might be more important than recent weight h i s t o r y and provide an a l t e r n a t i v e i n t e r p r e t a t i o n for the d i f f e r e n c e found between obese and f l u c t u a t o r subjects on the expectancy change task. Similar numbers of f l u c t u a t o r and obese subjects reported that they were presently d i e t i n g ; thus, an explanation of t h i s experimental f i n d -ing based on differences i n eating patterns would be inappropriate. The numbers of subjects who indicated they were presently on a d i e t i n the average,fluctuator and obese groups were res p e c t i v e l y , 1, 12, and 9. Again t h i s information was obtained from s e l f - r e p o r t data and did not i n d i c a t e the nature or the extent of these dietary r e s t r i c t i o n s . The g e n e r a l i z a b i l i t y of the present findings i s l i m i t e d i n that the sample used i n the i n v e s t i g a t i o n was r e s t r i c t e d to p a r t i c i p a n t s who were female, college students between 18-25 years of age. Also, a l l subjects i n t h i s study had volunteered to p a r t i c i p a t e i n an exper-iment on body b u i l d , behavior, and personality and had completed a questionnaire on recent weight h i s o t r y (Appendix A) so that p a r t i c i -pants were aware that the i n v e s t i g a t i o n was concerned with body weight. In most respects the present sample was comparable to those used i n other i n v e s t i g a t i o n s of experimental differences between obese and normal i n d i v i d u a l s , and the s e l e c t i o n of t h i s sample ensured that meaningful comparisons could be made between the r e s u l t s of t h i s inves-t i g a t i o n and r e s u l t s from previous studies. 53 Although the obese subjects i n the present i n v e s t i g a t i o n were over-weight according to the experimental c r i t e r i a of most other i n v e s t i g a -tions i n t h i s area, i t may be the case that the i n c l u s i o n of more sub-j e c t s who were highly overweight would produce somewhat d i f f e r e n t r e s u l t s i n inv e s t i g a t i o n s of t h i s s o r t . Some researchers have found that d e f i n i t e l y obese subjects behave d i f f e r e n t l y from moderately over-weight i n d i v i d u a l s i n a number of experimental s i t u a t i o n s (Nisbett, 1972; Rodin, 1975). Results from these studies have indicated that extremely overweight i n d i v i d u a l s behave s i m i l a r l y to average i n d i v i d u a l s i n s i t u a t i o n s i n v o l v i n g prominent external s t i m u l i . In the present i n v e s t i g a t i o n c o r r e l a t i o n s between the degree of overweight as measured by the t r i c e p s s k i n f o l d and the experimental measures indicated that degree of overweight was p o s i t i v e l y r e l a t e d to some measures of perfor-mance on the experimental tasks f o r subjects i n the co n s i s t e n t l y obese group, i . e . , errors on the l a s t 30 cards of the expectancy change task, <. t r i a l s to c r i t e r i o n and i n t r a l i s t i n t r u s i o n s on the f i r s t l i s t of the paired associate task, and the t o t a l number of errors and i n t r a l i s t i n trusions on the tr a n s f e r l i s t of the paired associate task. Future research i n t h i s area might include groups of both moderately over-weight and highly overweight i n d i v i d u a l s to determine whether degree of obesity i s r e l a t e d to the d e f i c i t - i n - r e s p o n s e - i n h i b i t i o n e f f e c t . For example, extremely overweight subjects may have more d i f f i c u l t y i n suppressing potent responses than moderately overweight subjects. Implications f o r Treatment Other investigators (Singh, 1973; Sikes, 1974) have discussed the somewhat d i f f e r e n t implications of the stimulus-binding and the 54 d e f i c i t - i n - r e s p o n s e - i n h i b i t i o n theories f o r the treatment of obese i n d i v i d u a l s . According to the stimulus-binding view, treatment should concentrate on i d e n t i f y i n g environmental s t i m u l i which e l i c i t inappro-p r i a t e eating responses and attempting to modify the environment so that more appropriate eating behavior w i l l take place. The d e f i c i t - i n -response- i n h i b i t i o n theory indicates that treatment e f f o r t s should concentrate on response tendencies and attempt to replace inappropriate responses with other behavior. Also, i f obese people have more d i f f i -c u l t y than average i n d i v i d u a l s i n i n h i b i t i n g an ongoing response, i t would seem that treatment procedures aimed at discontinuing the eating response e a r l i e r i n a meal would be quite e f f e c t i v e . For instance, obese i n d i v i d u a l s could be instruc t e d to place appropriate portions of food on t h e i r plates p r i o r to a meal rather than helping themselves to food at the table. A l l other food should be out of sight. When the food on the pl a t e has been consumed, the overweight i n d i v i d u a l would be instructed, to leave the dining area. I f , i n f a c t , the overweight condition i n obese i n d i v i d u a l s i s at le a s t i n part due to t h e i r con-suming more food at regular meals than i s necessary to s a t i s f y t h e i r appetites, then the use of t h i s procedure would seem to be quite e f f e c t i v e . This technique aimed at reducing overeating i s one of a number of procedures included i n the behavioral treatment program outlined by Stuart (1967) which was designed both to l i m i t environ-mental s t i m u l i which e l i c i t inappropriate eating responses and to replace response habits which are contributing to the overweight condition. The r e s u l t s from both the present i n v e s t i g a t i o n and other studies have indicated that there are behavioral differences between 55 obese i n d i v i d u a l s who are co n s i s t e n t l y overweight and those who are highly v a r i a b l e and also between obese i n d i v i d u a l s who are extremely overweight and those who are moderately overweight. Further experimen-t a l research on subgroups of obese i n d i v i d u a l s and the t r a n s l a t i o n of research findings into p o t e n t i a l l y e f f e c t i v e treatment procedures f o r i n d i v i d u a l c l i e n t s might r e s u l t i n an increase i n successful treatment outcomes for obese patients. For instance, according to the findings of the present i n v e s t i g a t i o n treatment procedures aimed at changing response tendencies would probably be more e f f e c t i v e with co n s i s t e n t l y obese than f l u c t u a t o r c l i e n t s . Based on r e s u l t s from other i n v e s t i g a -tions (Nisbett, 1972; Rodin, 1975), an e f f e c t i v e treatment program f o r moderately overweight i n d i v i d u a l s might focus on modifying the environ-mental s t i m u l i which e l i c i t inappropriate eating behavior while a dif-^ ferent treatment emphasis may be more appropriate with extremely obese i n d i v i d u a l s . Future Directions These are ten t a t i v e speculations and the need f o r more basic research on obesity i s great i f we are to learn more about t h i s condi-t i o n and to gain knowledge about various types of obesity which can be used i n formulating treatment programs for overweight patients. There are several d i r e c t i o n s which future research might take to advance the knowledge i n t h i s area. More investigations could be run with experi-mental tasks which allow a comparison of the predictions of the stimulus-binding and d e f i c i t - i n - r e s p o n s e - i n h i b i t i o n theories. These studies could use several categories of obese subjects, e.g., consis-t e n t l y overweight versus f l u c t u a t o r and extremely overweight versus 56 moderately overweight, i n a d d i t i o n to a group of average subjects to determine whether obese subgroups d i f f e r from each other and from the average group i n other experimental s i t u a t i o n s . Other s t u d i e s might compare f l u c t u a t o r and c o n s i s t e n t l y obese subjects on some of the e x t e r n a l cue manipulations p r e v i o u s l y used by Schachter and others. Whether an i n d i v i d u a l becomes overweight or not i s probably deter-mined by a host of f a c t o r s i n c l u d i n g h e r e d i t y , d i e t (which i s a f u n c t i o n of socioeconomic s t a t u s , e t h n i c i t y , and other v a r i a b l e s ) , metabolism, and a c t i v i t y l e v e l . Obesity i s probably a complexly determined c o n d i -t i o n and the p o p u l a t i o n of overweight i n d i v i d u a l s seems to be h i g h l y heterogeneous. The present i n v e s t i g a t i o n i n d i c a t e s that weight h i s t o r y p l a y s an important r o l e i n the determination of behavior i n obese i n d i v i d u a l s . Future research should attempt to i s o l a t e other f a c t o r s which have a s i g n i f i c a n t bearing on t h i s c o n d i t i o n . 57 REFERENCES Allsopp, J.F. and Eysenck, H.J. Personality as a determinant of paired-associates learning. Perceptual and Motor S k i l l s , 1974, 39, 315-324. Bone, R.N. 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E f f e c t of cue prominence and subject weight on human food-directed performance. Journal of Personality and S o c i a l  Psychology, 1974, 29, 843-848. Marascuilo, L.A. Large-sample multiple comparisons. Psychological  B u l l e t i n , 1966, 65, 280-290. Melton, A.W. Materials for use i n experimental studies of learning and retention of verbal habits. Mimeographed Manuscript, University of Missouri, 1940. Metropolitan L i f e Insurance Company. New weight standards for men and women. S t a t i s t i c a l B u l l e t i n , 1959, 40, 1-4. Nisbett, R.E. Taste, deprivation, and weight determinants of eating behavior. Journal of Personality and S o c i a l Psychology, 1968, 10, 107-116. Nisbett, R.E. Hunger, obesity, and the ventromedial hypothalamus. Psychological Review, 1972, 79, 433-453. N u t r i t i o n Canada. N u t r i t i o n : a National P r i o r i t y . Ottawa: Information Canada, 1973. Pervin, L.A. R i g i d i t y i n neurosis and general personality functioning. Journal of Abnormal and S o c i a l Psychology, 1960, 61, 389-395. Pett, L.B. and O g i l v i e , G.F. The Canadian weight-height survey, In J . Brozek (Ed.) Body Measurements and Human N u t r i t i o n . D e t r o i t : Wayne State University Press, 1956. P l i n e r , P.L. E f f e c t s of cue salience on the behavior of obese and normal subjects. Journal of Abnormal Psychology, 1973, 82, 226-232. P r i c e , J . and Grinker, J . E f f e c t s of degree of obesity, food depriva-t i o n , and p a l a t a b i l i t y on eating behavior of humans. Journal of  Comparative and P h y s i o l o g i c a l Psychology, 1973, 8_5, 265-271. Rodin, J . E f f e c t s of d i s t r a c t i o n on the performances of obese and normal subjects. Journal of Comparative and P h y s i o l o g i c a l  Psychology, 1973, 83, 68-75. Rodin, J. E f f e c t s of obesity and set point on taste responsiveness and ingestion i n humans. 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Obesity and Health. (U.S.P.H.S. Publication No. 1485) Washington, D.C.: U.S. Government Printing Office, 1966. Wechsberg, J. La nature des choses. The New Yorker, 1975, 51^, 23, 34-48. Winer, B.J. S t a t i s t i c a l principles in experimental design. New York: McGraw-Hill, 1962. 60 Wollersheim, J.P. The effectiveness of group therapy based upon learn-ing principles in the treatment of overweight women. Journal of  Abnormal Psychology, 1970, 7_6, 462-474. Wyden, P. The Overweight Society. New York; William Morrow, 1965. 61 APPENDIX A I n i t i a l Weight Questionnaire NAME PHONE NUMBER AGE HEIGHT WEIGHT How would you describe your p h y s i c a l b u i l d at the present time i n comparison to other females of approximately the same age? (Select one) D e f i n i t e l y Underweight S l i g h t l y Underweight Average S l i g h t l y Overweight D e f i n i t e l y Overweight During the past two years what i s the least that you have weighed (not including v a r i a t i o n s due to serious i l l n e s s or pregnancy)? How would you describe your phy s i c a l b u i l d at your lowest weight i n comparison to other females of approximately the same age? (Select one) D e f i n i t e l y Underweight S l i g h t l y Underweight Average S l i g h t l y Overweight D e f i n i t e l y Overweight During the past two years what i s the most that you have weighed (not including v a r i a t i o n s due to serious i l l n e s s or pregnancy)? How would you describe your phy s i c a l b u i l d at your highest weight i n comparison to other females of approximately the same age? (Select one) D e f i n i t e l y Underweight _ _ _ _ _ S l i g h t l y Underweight Average S l i g h t l y Overweight D e f i n i t e l y Overweight During the past two years what has your most frequent weight been? The information obtained i n t h i s form w i l l be treated e n t i r e l y c o n f i -d e n t i a l l y . Names and telephone numbers w i l l be u t i l i z e d only by the major inves t i g a t o r to contact volunteers f o r the research project. A l l data obtained i n the study w i l l be analysed using code numbers for i n d i v i d u a l p a r t i c i p a n t s to guarantee anonymity. Penny Aves Department of Psychology Univ e r s i t y of B r i t i s h Columbia 62 APPENDIX B Experimental Consent Form MAJOR INVESTIGATOR: PENNY AVES FACULTY SUPERVISOR: DR. JERRY WIGGINS Since t h i s i s a study r e l a t i n g to normal weight f l u c t u a t i o n s , we w i l l be unable to include i n d i v i d u a l s who are now pregnant or l a c t a t i n g or who have had any serious i l l n e s s within the past s i x months which might a f f e c t t h e i r weight, e.g., hepetitus, diabetes, etc. I understand the above r e s t r i c t i o n s on experimental subjects. I have been informed of the procedures involved i n t h i s experiment and agree to p a r t i c i p a t e i n the tasks which have been described to me. I also understand that I am free to terminate my p a r t i c i p a t i o n i n the experiment at any time and for any reason. SIGNATURE DATE APPENDIX C I n i t i a l and Transfer L i s t s used i n Paired Associate Task L i s t A - I n i t i a l P a i rs noxious sudden western bashful standard unshut c l a s s i c prepared erect absent rounded f a u l t l e s s yellow insane ample e v i l random double overt complete zigzag clumsy basic gloomy L i s t B - I n i t i a l P a i rs in j ured hidden u p h i l l c a r e f u l f e l i n e adept overgrown distant yawning grouchy twisted f e a r l e s s joyous mammouth quiet shining vocal barren extinct nomad wholesome devout stubborn l i t t l e L i s t A - Transfer noxious clumsy western double standard prepared c l a s s i c bashful erect gloomy rounded sudden yellow unshut ample f a u l t l e s s random complete overt e v i l zigzag absent basic insane L i s t B - Transfer i n j ured devout u p h i l l barren f e l i n e distant overgrown c a r e f u l yawning l i t t l e twisted hidden joyous adept quiet f e a r l e s s vocal nomad extinct shining wholesome grouchy stubborn mammouth 64 APPENDIX D Instructions f o r the F i r s t L i s t of the Paired Associate Task In the space i n front of you a number of pairs of words w i l l appear. When I s t a r t the machine, you w i l l see the f i r s t word and a f t e r about two seconds you w i l l see the f i r s t word again along with the second word. Your task w i l l be to learn to connect or associate the p a i r so when the f i r s t word appears you c a l l out the second word before i t appears i n the space. We'll go through the l i s t once, and I'd l i k e you to j u s t watch c a r e f u l l y and t r y to remember as many pair s as you can. A blank space w i l l appear a f t e r the l a s t p a i r and when the f i r s t word appears again I'd l i k e you to t r y and c a l l out the second word. We'll continue to go through the l i s t i n t h i s manner time a f t e r time u n t i l you've cor-r e c t l y a nticipated a l l of the words i n the l i s t f o r two consecutive t r i a l s . Your score w i l l be based on the t o t a l number of correct responses you make so t r y and give a response to each s i n g l e word. There i s no penalty f o r guessing so even i f you're unsure of the response f e e l free to guess because I'm interested as much i n the kinds of errors you make as i n the number of errors. Do you have any questions? Now, w e ' l l go through the l i s t once and j u s t watch c a r e f u l l y and tr y to remember the p a i r s . When the l i s t has gone by once, I ' l l t e l l you and you can s t a r t c a l l i n g out the responses. Remember, there's no penalty f or wrong answers so guess i f you can. (The l i s t i s presented one time to the subject.) Now s t a r t c a l l i n g out the responses.-65 APPENDIX E Instructions f o r the Transfer L i s t of the Paired Associate Task This task w i l l consist of the same items but the words w i l l be paired d i f f e r e n t l y . As before, go through the l i s t once j u s t watching c a r e f u l l y and t r y i n g to remember the p a i r s . After the f i r s t exposure, anytime you think you know the correct response, j u s t c a l l i t out. Your score w i l l be based on the number of correct responses you make i n ten t r i a l s . Remember, there's no penalty f o r guessing so i f you're unsure of a response f e e l free to guess because I'm interested as much i n the kinds of errors you make as i n the number of errors. (The l i s t i s presented one time to the subject). Now s t a r t c a l l i n g out the responses. APPENDIX F Weight History and Medical Information Questionnaire NAME AGE Do you feel that your present weight i s the best weight for you, or that you are over your best weight or under it? (Check one) Over best weight Under best weight Just right If you are over or under your best weight, indicate by how many pounds. Have you ever been overweight in the past? (Check one) Yes No If so, during which period(s) of your l i f e have you been overweight? (Check appropriate items) Childhood (1-8 years) Pre-Teens (9-11 years) Adolescence (12-18 years) Adult (19 years or later) Whick of the following statements best describes your present eating behavior? (Check one) Am on a diet right now to lose weight Diet from time to time but not now Don't diet but never eat certain fattening foods Once in awhile cut down on fattening foods for a few days, but in general pay no attention to weight Eat what I want with no concern about gaining weight If you diet, approximately how many times do you go on a diet during a year? Are you presently taking any form of medication? (Check appropriate items) Oral contraceptives Diet P i l l s Diuretics Other (please specify) 67 T y p i c a l l y , how long i t your menstrual cycle? (days) If you are quite i r r e g u l a r , what i s the range of your cycle lengths? (for example, 28-40 days) days to days How many days has i t been since you l a s t started menstruating? (days) How many days has i t been since you l a s t f i n i s h e d menstruating? (days) APPENDIX G Summary of Results Mailed to Experimental Participants Department of Psychology The University of British Columbia As you may r e c a l l , several months ago you participated in a psychology experiment involving the relationship of body build to personality and behavior. At that time I told you that everyone who had helped me by participating in the experiment would receive a copy of the summary of the experimental results. The data have now been analysed and the following section is a summary of the experimental findings. Participants in the study were divided into three groups on the basis of recent weight history and present weight classifications. These groups were consistently average, consistently overweight, and fluctuators (subjects whose weights over the past two years had varied between the average and overweight classifications). One of the tasks you participated in involved guessing the colors of cards in a stack. The f i r s t 90 cards were 75% black and 25% red while the last 30 cards were a l l red. There were no differences between groups on the f i r s t part of the task; however, on the last part (when a l l of the cards were red) there was a significant difference between groups in terms of the number of incorrect guesses made. Con-sistently overweight participants made significantly more errors than either average or fluctuator subjects. This finding is consistent with the deficit-in-response-inhibition theory which maintains that 69 overweight people have greater d i f f i c u l t y in changing established response tendencies than people of average weight. In the present study, however, only people who had been consistently overweight for the past two years experienced more d i f f i c u l t y in changing an established response. The other experimental task involved learning two l i s t s , each consisting of 12 pairs of adjectives. There were no significant differences between the three groups on performance measures for either l i s t : thus, in this situation overweight subjects did not perform worse than average subjects when required to change established response tendencies. Performance on this task might have been i n f l u -enced by other factors such as memory and imagery a b i l i t y which could have been more important in this situation than weight status. The personality questionnaire that you completed was a measure of extraversion and neuroticism. Results from an analysis of these scores indicated that there were no differences between the three weight groups on either extraversion or neuroticism. This also indi -cated that the difference in performance on the card color-guessing task was not due to personality differences on extraversion or neuroticism between the three weight groups. The results from this study indicate that i t is important to consider recent weight history as well as present weight when investi-gating behavioral differences between overweight and normal individuals. Since the population of overweight individuals is probably quite heterogeneous, i t is l i k e l y that future research w i l l identify other important factors which d i f f e r e n t i a t e between groups of overweight i n d i v i d u a l s . Though the r e s u l t s of t h i s p a r t i c u l a r experiment are not s u f f i c i e n t i n themselves to permit a d i r e c t a p p l i c a t i o n of these findings to treatment procedures for overweight i n d i v i d u a l s , i t i s hoped that cumulative r e s u l t s from investigations of t h i s type w i l l soon begin to provide important information which can be applied i n formulating treatment programs f o r s p e c i f i c types of overweight i n d i v i d u a l s . Thank you again for your help. Penny Aves 

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