Boys vs. girls: Gender differences in the neural development of trust and reciprocity depend on social context

tTrust and cooperation increase from adolescence to adulthood, but studies on gender differences in thisdevelopment are rare. We investigated gender and age-related differences in trust and reciprocity andassociated neural mechanisms in 43 individuals (16–27 years, 22 male). Participants played two multi-round trust games with a cooperative and an unfair partner. Males showed more basic trust towardsunknown others than females. Both genders increased trust during cooperative interactions, with nodifferences in average trust. Age was unrelated to trust during cooperation. During unfair interactionsmales decreased their trust more with age than females. ROI analysis showed age-related increases inactivation in the temporo-parietal junction (TPJ) and dorsolateral prefrontal cortex (dlPFC) during coop-erative investments, and increased age-related caudate activation during both cooperative and unfairrepayments. Gender differences in brain activation were only observed during cooperative repayments,with males activating the TPJ more than females, and females activating the caudate more. The find-ings suggest relatively mature processes of trust and reciprocity in the investigated age range. Genderdifferences only occur in unfair contexts, becoming more pronounced with age. Largely similar neuralactivation in males and females and few age effects suggest that similar, mature cognitive strategies areemployed.