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Deception in facial expressions of pain : strategies to improve detection

University of British Columbia

Research suggests that clinicians assign greater weight to nonverbal expression than to patients' self-report when judging the location and severity of their pain. However, it has also been found that pain patients are fairly successful at altering their facial expressions of pain, as their deceptive and genuine pain expressions show few differences in the frequency and intensity of pain-related facial actions. The general aim of the present research was to improve the detection of deceptive pain expressions using both an empirical and a clinical approach. The first study had an empirical focus to pain identification, and provided a more detailed description of genuine and deceptive pain expressions by using a more comprehensive range of facial coding procedures than previous research. A review of research on facial expressions, pain research and deception suggested that facial analyses of genuine and deceptive pain expressions could be expanded to include new variables such as temporal patterns and contiguity of facial actions, as well as an increased focus on facial cues thought to be indicative of lying. Low back patients (n=40) were videotaped at rest and while undergoing a painful straight leg raise under three sets of instructions: 1) to genuinely express any pain they felt, 2) pretend that it didn't hurt, 3) to fake pain without moving their legs. FACS coding was used to describe and quantify their facial activity and the neutral, genuine pain, masked pain and faked pain expressions were compared on the number, type, intensity, temporal qualities , and contiguity in time of individual facial actions, as well as the incidence of facial actions thought to be indicative of deception. Findings confirmed the difficulty of discriminating the various facial expressions, but indicated that the faked pain expressions show a greater number of pain-related and non pain-related actions, remain at peak intensity longer, and last for a longer period of time than do genuine pain expressions. The difference between masked pain and neutral expressions were more subtle, with masked pain expressions exhibiting a greater frequency of mouth opening and residual movement of the eyebrows. The second study was more clinical in nature and was designed to see i f specific training could improve the detection skills of naive judges by increasing their knowledge and awareness of possible cues to deception. University students (60 male, 60 female) were randomly assigned to one of four experimental groups: l)control, 2) corrective feedback, 3) deception training, and 4) deception training plus feedback. Each subject was shown the videotaped data of the pain patients in all four conditions (neutral expressions, genuine, masked and faked pain expressions). For each videoclip, the subjects rated the intensity and unpleasantness of the pain experienced by the patient, decided which category each of the four videoclips represented, and described which cues they used to make their decision. There were significant individual differences in accuracy, with accuracy being unrelated to past pain experience, empathy, or the number or type of facial cues used. There was, however, a significant sex difference in judgement accuracy, with females being more accurate than males. Results also showed that immediate corrective feedback led to significant improvements in subjects' detection accuracy, while there was no support for the use of an information-based training program.

Thesis/Dissertation

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2009-03-17

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http://hdl.handle.net/2429/6119

Psychology

University of British Columbia

UBCV

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