Abstract
The experience of pain includes sensory, affective, cognitive and behavioral components (Boccard, 2006) and leads to the contraction of specific facial muscles (Kunz et al., 2012) that are, to some extent, encoded in the mental representation of onlookers (Blais et al., in revision). Exposition to facial expressions of pain has been demonstrated to entail a neural emphatic experience in the viewer (Botvinick et al. 2005, Lamm et al. 2007), which varies as a function of subjects’ empathy level (Saarela et al. 2007). This experiment aims to verify the impact of empathy variations on the facial features stored by individuals in their mental representation of pain facial expressions. 54 participants (18 males) were tested with the Reverse correlation method (Mangini & Biederman, 2004). In 500 trials, participants chose from two stimuli the face that looked the most in pain. For each trial, both stimuli consisted of the same base face with random noise superimposed, one with noise pattern added, and the other subtracted. Empathy level was measured using the Emotional Quotient test (Baron-Cohen & Wheelwright, 2004) and used as weight to generate two Classification images (CI) for high-empathy and low-empathy levels. Those CIs were then presented to an independent sample (N=24) who identified High-empathy CI as significantly more intense in regions usually associated with pain expression (i.e. brow lowering [x2=24, p< 0.005], nose wrinkling/upper lip raising [x2=10.67, p< 0.05]) and eyes narrowing [x2=6, p< 0.05]). A CI of difference was then generated (i.e. High-empathy CI - Low-empathy CI), and submitted to a Stat4CI cluster test (Chauvin et al., 2005) resulting in a significant difference in the mouth area (ZCrit=2.7, K=80, p< 0.025). Taken together these results suggest that mental representation of pain expression varies with individual differences in empathy.
Acknowledgement: Social Sciences and Humanities Research Council