Are you safe or should I go? : How perceived trustworthiness and probability of a sexual transmittable infection impact activation of the salience network

Abstract

Functional imaging studies indicate that both the assessment of a person as untrustworthy as well as the assumption that a person has a sexually transmitted infection are associated with activation in regions of the salience network. However, studies are missing that combine these aspects and investigate the perceived trustworthiness of individuals previously assessed with high or low probability of a sexually transmitted infection. During fMRI measurements, 25 participants viewed photographs of people pre-classified as having high or low HIV probability and judged their trustworthiness. In a post-rating, stimuli were rated for trustworthiness, attractiveness and HIV probability. Persons pre-classified as HIV- in contrast to those pre-classified as HIV+ were rated more trustworthy and with lower HIV probability. Activation in medial orbitofrontal cortex was higher for those rated and pre-classified as HIV- than HIV+. Based on the individual ratings, but not the pre-classification, there was significantly higher activation in Insula, amygdala, anterior cingulate cortex and Nucleus accumbens in response to untrustworthy than to trustworthy faces. Activation of the salience network occurred when a person was judged as untrustworthy, but not according to a pre-classification. Activation in the medial orbitofrontal cortex, a structure associated with reward was enhanced when a person was perceived as trustworthy, and also when a person was pre-classified with low HIV probability. Our findings suggest that trustworthiness and HIV- perception have consistency across samples, while the perception of risk and associated activation of the salience network has restricted cross-sample consistency. Significance Statement: Whether a person is trustworthy or might pose a risk to one’s own health must be decided in a few moments and based on limited characteristics. The salience network as an “alarm system” should be involved in these evaluative processes. This paper reports the results of neural activation in trustworthiness judgments of naturalistic stimuli of persons pre-categorized as HIV+ or HIV-. We find activation in medial orbitofrontal cortex for people evaluated as trustworthy and for people pre-categorized as HIV-. For people judged as untrustworthy, activation in insula, amygdala, anterior cingulate cortex and Nucleus accumbens is revealed. These findings suggest a safety signal in the medial orbitofrontal cortex and an involvement of the salience network in risk detection.