Denying Humanity: The distinct neural correlates of blatant dehumanization

Recent behavioral work demonstrates that many people view low-status groups as less 'evolved and civilized' than high-status groups. Are these people using blatant expressions of dehumanization simply to express strong dislike towards other groups? Or is blatant dehumanization a process distinct from other negative assessments? We tested these competing hypotheses using functional neuroimaging. Participants judged ten groups (e.g. Europeans, Muslims, rats) on four scales: blatant dehumanization, dislike, dissimilarity and perceived within-group homogeneity. Consistent with expectations, neural responses when making ratings of dehumanization diverged from those when judging the same targets on the other related dimensions. Specifically, we found regions in the left inferior parietal cortex (IPC) and left inferior frontal cortex (IFC) that were selectively parametrically modulated by dehumanization ratings. The pattern of responses in the left IFC was also consistent with animalistic dehumanization: high responses to low-status human groups and animals, and lower responses to high- status human groups. By contrast, a region in the posterior cingulate cortex was parametrically sensitive specifically to liking. We therefore demonstrate a double dissociation between brain activity associated with judgments of blatant dehumanization and judgments of dislike.