Theory of Mind Following the Violation of Strong and Weak Prior Beliefs

Recent work in psychology and neuroscience has revealed differences in impression updating across social distance and group membership. Observers tend to maintain prior impressions of close (vs. distant) and ingroup (vs. outgroup) others in light of new information, and this belief maintenance is at times accompanied by increased activity in Theory of Mind regions. It remains an open question whether differences in the strength of prior beliefs, in a context absent social motivation, contribute to neural differences during belief updating. We devised a functional magnetic resonance imaging study to isolate the impact of experimentally induced prior beliefs on mentalizing activity. Participants learned about targets who performed 2 or 4 same-valenced behaviors (leading to the formation of weak or strong priors), before performing 2 counter-valenced behaviors. We found a greater change in activity in dorsomedial prefrontal cortex (DMPFC) and right temporo-parietal junction following the violation of strong versus weak priors, and a greater change in activity in DMPFC and left temporo-parietal junction following the violation of positive versus negative priors. These results indicate that differences in neural responses to unexpected behaviors from close versus distant others, and ingroup versus outgroup members, may be driven in part by differences in the strength of prior beliefs.