Trust and risk perception influence brain activity in health assessments

Perceiving whether another person is a personal health risk requires quickly assessing their trustworthiness. With limited characteristics available, implicit assumptions often influence risk perception. Research in this area has pointed to brain regions that may be involved in perceiving others as untrustworthy or as carriers of sexually transmitted diseases (STDs).

However, the relationship between brain activity, perceived trustworthiness of others, and perceived likelihood of acquiring an STD was unclear prior to a recent study published in eNeuro. In the study led by Daniela Mier at the University of Konstanz, participants viewed pictures of people and assessed their trustworthiness. The same images had been evaluated in a previous study as having high or low odds of HIV transmission. People in the images with lower perceived odds of HIV transmission were generally considered more trustworthy in the current study by Mier's group.

Brain imaging revealed that perceived low risk of HIV transmission and high trustworthiness both resulted in higher activation of a brain region in the reward network, which may be a "safety signal" in the brain. Conversely, people with higher perceived odds of HIV transmission were more often deemed untrustworthy by participants. But comparisons across groups showed that distrust alone-and not necessarily high likelihood of HIV transmission-led to more activation of brain regions in a different network called the salience network, which may serve as the brain's "alarm signal."

Ultimately, how humans perceive others seems to alter the activation of reward and salience networks that might play a role in making assessments about the risk others pose to one's own safety.