Facial Width-to-Height Ratio as a Cue of Threat : An Initial Event-Related Potential Study

The background for the present study is that facial width-to-height ratio (fWHR) is suggested to function as an evolutionary cue for threatening behavior such as perceived aggression. With a novel approach, in this pilot study, we explored whether fWHR can be detected in observers brain responses measured by event-related potentials (ERP), specifically, the Late Positive Potential (LPP) component (400-3000ms after stimuli onset). The hypothesis was that faces with a high fWHR would elicit a larger LPP amplitude than faces with a low fWHR. The results showed that faces with high fWHRs were indeed perceived as more aggressive and elicited significantly greater LPP amplitudes. The conclusion lends initial support to fWHR serving as a facial cue with evolutionary relevance. We caution that future full-length studies need to take the current small-scale study's limitations into consideration