Breakdown intention-based outcome evaluation after transient right temporoparietal junction (rTPJ) deactivation

People judge the nature of human behaviors based on underlying intentions and possible outcomes. Recent studies have demonstrated a causal role of the right temporoparietal junction (rTPJ) in modulating both intention and intention-based outcome evaluations during social judgments. However, these studies are mainly extended under hypothetical scenarios with socially undesirable contexts (bad/neutral intentions and bad/neutral outcomes), leaving the question of whether the rTPJ plays a similar role in modulating social judgments under scenarios with good intentions and good outcomes underexplored. In the current study, participants were instructed to make fairness judgments as a third party toward the monetary allocations from one dictator to another responder. Critically, in some cases, the initial allocation by the dictator could be reversed by the computer, yielding combinations of good/bad intentions with good/bad outcomes. Anodal (n = 20), cathodal (n = 21), and sham (n = 21) transcranial direct current stimulation (tDCS) over the rTPJ were randomly assigned to 62 subjects to further examine the effects of stimulation over the rTPJ in modulating intention-based outcome evaluation. We have identified a consistent intention-oriented attribution regardless of the fairness of outcomes in the baseline condition across groups. Moreover, cathodal tDCS over the rTPJ compared to the anodal and sham stimulations diminished the goodness ratings towards good/bad outcomes when the intentions are hyperaltruistic and showed no difference with outcome ratings under unknown and bad intentions. Our results provide the first evidence that deactivating the rTPJ disrupted intention-oriented attribution in social judgments, mainly by reducing the goodness rating towards both good/bad outcomes when the intentions are hyperaltruistic, but not by enhancing the permission of good outcomes when the intentions are bad/unknown. Our findings argue for a causal role of the rTPJ in modulating intention-based social judgments that may also rely on contextual salience.