Subliminal Exposure to Putrescine Does Not Affect Aggressiveness Judgments for Male Faces Varying in Race and Facial Width-to-Height Ratio

We discuss two relatively understudied yet important phenomena relevant to the ecologically crucial task of gathering reliable information from human faces. First, facial width-to-height ratio (fWHR) predicts aggressiveness judgments and is associated with aggression-related behavior and life history outcomes. A significant body of research indicates fWHR is an honest evolutionary signal of propensity to aggression yet little is known about how or if this signal is preserved in judgments across race boundaries. Evidence for a universal relationship between increased fWHR and enhanced aggression perception has been found using Asian and white face stimuli, but race moderated the relationship between high fWHR and ratings in a pain ascription task using black and white faces. Second, we examine research on olfactory cues to face perception and focus particular attention on the possibility that face judgments may be influenced by putrescine, an organic compound found recently to heighten threat and escape-related cognitions in a single subliminal odor presentation study. Here we probe how fWHR and face race interact in aggression judgments during subliminal exposure to putrescine and a control condition. We present a standardized method of subliminal putrescine delivery and find null effects of putrescine on face judgments. Overall, our primarily white participants show a reduced difference in aggressiveness ratings to black faces from low to high levels of fWHR compared to the same contrast in white face stimuli, consistent with an account in which black faces are not perceived with the same configural precision as white faces.