Tapping Trust Task (TTT): Investigating the mechanisms of interpersonal synchrony in the trust game

Abstract

Interpersonal synchrony has repeatedly been shown to increase affiliation, similarity, and prosocial decision making. As yet, however, the effect of interpersonal synchrony on trust and its neural mechanisms have not been investigated. The current study therefore investigated the behavioral and neural mechanisms of trust as a function of interpersonal synchrony in a tapping task. Participants performed three finger-tapping rounds, each with a different age- and sex-matched partner, of which one tapped in synchrony, another tapped out-of-sync and a third one did not tap (control condition). After tapping, participants played a trust game in the MRI-scanner with all three tapping partners. Participants could choose how many coins to invest in each of the tapping partners. The invested amount was tripled and participants were told that the tapping partner would later decide how many coins he/she would reciprocate. We hypothesized that playing the trust game with synchronous partners would elicit higher trust than playing with the asynchronous or control partners. Higher trust was expected to be associated with ventral striatum and ventromedial prefrontal cortex activation. Also, we expected that trusting asynchronous and control partners would be associated with regions implicated in cognitive control and mentalizing. The results show no significant differences between conditions in both trust and neural activation. These null-results may be explained by multiple factors, such as the tapping task not being realistic and controlled enough, or lack of feedback during the trust game. In the future we plan to look into the role of these factors more closely.