Anonymity in sharing morally salient news: the causal role of the temporoparietal junction.

Considering the crucial role of morality in shaping one's reputation, exploring factors that modulate people's decision to share morally salient news is important. Previous studies suggested that self-expression and socializing are 2 key factors for news-sharing behaviors, suggesting the key role of anonymity in such decisions. Using functional magnetic resonance imaging (fMRI) and transcranial direct current stimulation (tDCS), the present study focused on how anonymity modulates the sharing of morally salient information, as well as its neural mechanisms. Results showed that compared to moral news, people were more reluctant to share immoral news, especially when they share it with their real names shown. On the neural level, we found that this effect was associated with the activity of the left temporoparietal junction (TPJ), as well as its functional connection to its right counterpart. Dynamic causal modeling analysis revealed the moral valence of news and the anonymity of sharing modulated the effective connectivity between the left TPJ and the middle frontal gyrus as well as the medial frontal gyrus. There was no significant difference when sharing news anonymously. Further, a followed-up tDCS experiment supported the causal role of the left TPJ in this behavioral effect. Taken together, these results suggested that people concern more about social repercussion, when they share the news with their real-names shown, especially when sharing immoral news, and this effect is associated with stronger neural activation in the left TPJ, as well as changes in its functional connectivity with other brain regions.