The present thesis deals with the concept of empathy for pain, its neurobiological underpinnings and modulations of the phenomenon. Empathy for pain is understood as the empathic response that occurs when recognising another in pain and entails at least the affective processes of actually felt pain in oneself. Cortical areas of importance for empathy for pain are the anterior insula and anterior cingulate cortex. Moreover, the phenomenon is correlated with high levels of empathy, as established by behavioural self-reports. Further, empathy for pain has been shown to be highly susceptible to modulatory factors giving rise to changes in the empathic response. Perceived fairness, perspective taking, intent and out-groups are all factors that can evoke change in the subsequent empathy for pain responses in humans. These modulatory factors provide insight into in- and out-group mechanisms. Cognitive strategies can regulate a diminished empathy for pain response, although further research is needed on how to cultivate and strengthen our ability to have empathy for another’s pain.
The facial width-to-height ratio (fWHR) is a measure of the cheekbone width divided by the height of the face from the upper lip to the brows. The metric is hypothesised to have evolved as an intra-sexual competition mechanism in males, where large fWHRs are thought to signal both threat and aggression. The fWHR is suggested to subtly resemble angry facial expressions, which, in turn, also signal threat. The late positive potential (LPP) and the vertex positive potential (VPP) are two event-related potentials (ERPs) especially sensitive to emotional content. Studies have also found that viewing angry compared to neutral facial expressions elicit a stronger response on the LPP. However, no study has tested how responses to the fWHR and angry facial expressions elicit changes in the LPP or VPP. In this study, participants firstly rated how threatening faces were with either low or high fWHRs with neutral or angry facial expressions. Secondly, EEG-activity was recorded during a picture-viewing task of the same faces. In the first task, participants rated the faces with angry facial expressions as more threatening compared to all other faces, regardless of fWHR, although the high fWHRs were rated as more threatening than the low fWHRs. In the second task, LPP and VPP mean amplitudes were significantly higher for the angry, high fWHR face compared to all other faces tested. This suggests that an additive effect of both angry facial expressions and high fWHRs together creates the highest threat level in both subjective ratings as well as in ERP mean amplitudes. Further ERP research is needed on the relationship between fWHRs and anger to establish how the two features work both separately and together.