Sex differences in the decoding of pain-related body postures.

Abstract

Pain can be detected through nonverbal cues, including facial expressions, vocalisations, and body posture. While there are sex differences in how emotional expressions are recognized, these differences have not always been found for pain. One reason for this inconsistency may be methodological, as pain studies tend not to be designed to investigate individual differences in expression recognition. Also, few studies consider sex differences outside facial expression. This study applied an image degradation method used to examine individual differences in emotion recognition, to investigate sex differences in the decoding of pain body postures. Forty participants (20 male) were presented with a series of body posture images depicting pain at differing levels of image degradation. Happiness, anger and sadness expressions were also included for comparison. Results showed significant effects of image degradation, affect type, and actor sex. Females were rated as presenting more intense pain than males; this pattern was also found for fear, but not anger or happiness. The accuracy of pain intensity judgements was reduced as image clarity decreased. Male actors depicting pain were recognized with greater accuracy than female actors. Interestingly, similar patterns were found for anger and fear expressions. We conclude that sex has a significant influence on pain decoding under certain conditions, and while there are similarities with the way pain and core emotions are decoded, this may depend on the type of emotion presented. This also suggests that sex-related effects in the recognition of pain expressions may include body postural cues. Observer's judgements of pain displayed through body postures are driven by the sex of the person in pain.