Dorsomedial prefrontal cortex and cerebellar contribution to in‐group attitudes: a transcranial magnetic stimulation study

We tend to express more positive judgments and behaviors toward individuals belonging to our own group compared to other (out‐) groups. In this study, we assessed the role of the cerebellum and of the dorsomedial prefrontal cortex (dmPFC) – two regions critically implicated in social cognition processes – in mediating implicit valenced attitudes toward in‐group and out‐group individuals. To this aim, we used transcranial magnetic stimulation (TMS) in combination with a standard attitude priming task, in which Caucasian participants had to categorize the valence of a series of adjectives primed by either an in‐group or an out‐group face. In two behavioral experiments, we found an in‐group bias (i.e. faster categorization of positive adjectives when preceded by in‐group faces) but no evidence of an out‐group bias. Interestingly, TMS over both the dmPFC and over the (right) cerebellum significantly interfered with the modulation exerted by group membership on adjective valence classification, abolishing the in‐group bias observed at baseline. Overall, our data suggest that both the dmPFC and the cerebellum play a causal role in mediating implicit social attitudes.