Twin differences in the Minnesota Trust Game relate to neural mechanisms of suspiciousness

Spite sensitivity, or the fear that a person is willing to intentionally take a loss to ensure that another person will as well, may be a key component in understanding persecutory ideation (the belief that others want to harm you). We implemented a co-twin control design to examine potentially causal relationships among persecutory ideation, spite sensitivity, and neural activity and connectivity. Sixty-nine participants (23 monozygotic twin pairs and an additional 23 unpaired monozygotic twins) completed the Minnesota Trust Game-a social decision-making game played asynchronously with an anonymous partner that targets spite sensitivity by varying the incentives of the partner. Participants with more self-reported persecutory ideation (relative to those with lower persecutory ideation) trusted less even when the partner was incentivized to be fair. Similarly, computational modeling showed that increased persecutory ideation was associated with greater beliefs of a partner's spitefulness. Twins with greater beliefs of a partner's spitefulness (relative to their co-twins) also reported higher persecution. In addition, twin differences in left lateral OFC activation during the task were associated with spite sensitivity. These results point towards a potentially causal role of the lateral OFC on spite sensitivity, and in turn effects of spite sensitivity on persecutory ideation.