Evidence for a social function of the anterior temporal lobes: low-frequency rTMS reduces implicit gender stereotypes

By nature, stereotypes require processes of categorization or semantic association, including social information about groups of people. There is empirical evidence that the anterior temporal lobe (ATL) processes domain-general semantic information, and supports social knowledge. A recent study showed that inhibitory repetitive transcranial magnetic stimulation (rTMS) to the ATL reduced racial stereotypes on an implicit association test (IAT). However, it was not determined whether this was caused by changes to specific social, or general semantic processing, or both. The current study addresses these theoretical issues. The design investigated the effect of rTMS to the left or right ATL, or a sham stimulation, on a social IAT (gender stereotypes), a non-social IAT (living versus non-living associations), and a non-semantic control (Stroop) task. The results showed that low-frequency rTMS to both left and right ATL significantly reduced D-scores on the gender IAT compared to the sham group; however, there were no differences on the non-social IAT or the Stroop. The findings show the ATL has a role in mediating stereotypes, and the decrease of bias after stimulation could be due to weakening of social stereotypical associations either within the ATL or via a network of brain regions connected with the ATL.