Oxytocin and the Biological Basis for Interpersonal and Political Trust

Political scientists have documented the many ways in which trust influences attitudes and behaviors that are important for the legitimacy and stability of democratic political systems. They have also explored the social, economic, and political factors that tend to increase levels of trust in others, in political figures, and in government. Neuroeconomic studies have shown that the neuroactive hormone oxytocin, a peptide that plays a key role in social attachment and affiliation in non-human mammals, is associated with trust and reciprocity in humans (e.g., Kosfeld et al., Nature 435:673-676, 2005; Zak et al., Horm Beh 48:522-527, 2005). While oxytocin has been linked to indicators of interpersonal trust, we do not know if it extends to trust in government actors and institutions. In order to explore these relationships, we conducted an experiment in which subjects were randomly assigned to receive a placebo or 40 IU of oxytocin administered intranasally. We show that manipulating oxytocin increases individuals' interpersonal trust. It also has effects on trust in political figures and in government, though only for certain partisan groups and for those low in levels of interpersonal trust.