Abstract
The ability to perceive physical pain in others is a critical biological skill for adapted social interactions. People suffering from prosopagnosia often perform poorly when recognizing basic facial expressions of emotion. However, whether prosopagnosia also impairs the decoding of the facial expression of pain has not been investigated yet. To address this question, we tested PS, a pure case of acquired prosopagnosia previously shown to present a marked impairment and suboptimal information use (i.e., the mouth) during the decoding of static basic facial expressions of emotion. We first used a reverse correlation technique to extract the mental representations during the evaluation of pain intensity in PS and age-matched (AM) control participants. We then measured the accuracy at estimating pain intensity from ecological videos of individuals experiencing various levels of pain, as well as the categorization of pain among the basic facial expressions of emotion (i.e, happiness, surprise, sadness, anger, fear, disgust) plus neutral in PS and the AM controls. Firstly, the reverse correlation data revealed that PS’s mental representation differed from that of AM controls in the area between the eyes. More specifically, the brow lowering feature was less salient in PS’s mental representation of pain expressions. Interestingly, however, PS showed comparable performance with the AM controls for both the estimation of ecological pain intensity and the categorization of pain across facial expressions of emotion. Our data show that brow lowering and mouth upper-lip raising are salient features of the mental representations of physical pain facial expressions in healthy observers. Strikingly, however, PS reached comparable performance with the AM in the estimation and categorization of pain, despite relying mostly on the mouth. Our data reinforce the view that the mouth has more weight than the eye region when decoding pain from faces (Blais et al., 2019).