Implicit gender bias modulates lateral prefrontal cortex activity and rejection of female advice during cooperative decision making

Despite efforts to increase gender diversity in leadership, women remain undervalued, mainly due to gender stereotypes portraying females as less competent and of lower status. This study employs a novel mixed-gender dyad collaborative task with electroencephalography (EEG) and dipole source localization to investigate the neural mechanisms underpinning gender-biased rejection decisions in a real-time social context. In half of the trials, the male participants were designated as decision-makers, who evaluated their female partners' suggestions and provided the final team answer. EEG data collected from the male low-biased (LB) and high-biased (HB) groups, classified according to the Implicit Association Test (IAT), were analyzed during the decision periods which resulted in the rejection of female answers. The HB group rejected their female partners' choices at 57% in trials with conflict, which was similar in the LB group (55%). However, many rejections by the HB group resulted in wrong decisions (54%) which was significantly lower in the LB group (34%). Although criterion-based bias index from the signal detection theory could not explain this difference, a novel biased-rejection index (BRI), which measured the costly rejection behavior, could significantly separate the two male groups. Dipole source localization based on EEG during the entire decision period revealed significantly lower middle frontal gyrus (MFG), but higher inferior frontal gyrus (IFG) activation in the HB group compared to the LB group. Temporal dynamics analysis (resolution: 0.34 s) further showed (but not at a statistically-significant level) less activation in MFG for the HB group during the early stage, and a similar trend in SFG during the middle stage of cognitive processing. On the other hand, the moment magnitudes of IFG dipoles during the entire decision period were significantly correlated with the IAT D-scores, i.e. less IFG activation with lower implicit bias. Given the limitations of the study (lack of EEG from female decision-makers and 10-20 system montage), these findings suggest altered lateral prefrontal cortex (LPFC) activations as part of the neural correlates of gender-biased undervaluation of female contributions during a collaborative task.