In Religion We Trust: Psychophysiological Correlates of Emotion and Trust Among Religious In-Group Members

Social scientists from many disciplines have examined trust, including trust between those with different religious affiliations, emotional antecedents of trust, and physiological correlates of trust. However, little is known about how all of these factors intersect to shape trust behaviors. The current study aimed to examine physiological responses while individuals engaged in a trust game with a religious in-group or out-group member. Participants were randomly assigned to one of four conditions in which they were presented with the target’s profile before playing the game. In each of the conditions the target was described as either Catholic or Muslim and as someone who engaged in either costly signaling or anti-costly signaling behavior. In addition to assessing the amount of money invested as a behavioral measure of trust, physiological responses, specifically cardiac interbeat interval (IBI) and respiratory sinus arrhythmia (RSA), were measured. I hypothesized that when playing the trust game with a Catholic target as opposed to a Muslim target, Christian participants would (1) report being more similar to the target, (2) trust the target more, (3) invest more money in the target, (4) have a more positive outlook on the amount invested, and (5) show greater cardiorespiratory down-regulation, reflected by increases in IBI and RSA. Findings revealed that Christian participants reported greater similarity and showed a non-significant trend toward reporting a more positive outlook on (greater confidence in/satisfaction with) their investment decision when playing a Catholic versus Muslim target. Additionally, Christian participants who played an anti-costly signaling Catholic target showed greater cardiorespiratory down-regulation (increases from baseline for IBI, reflecting slower heart rate, and increases in RSA) than Christian participants who played an anti-costly signaling Muslim target. Results from this study echo previous findings suggesting that perceived similarity may facilitate trust. Findings also are consistent with previous research suggesting that religious ingroup or outgroup membership may not be as influential in shaping trust decisions if the trustee is costly signaling; for anti-signaling, however, cardiorespiratory down-regulation to a religious ingroup member may be apparent. These physiological signals may provide interoceptive information about a peer’s trustworthiness.