The oxytocin paradox

In 2005, Kosfeld et al. published their now seminal paper showing that intranasal oxytocin (OXT) administration increased interpersonal trust (Kosfeld et al., 2005). This finding spawned broad interest into the effects of OXT on social and emotional behavior in humans (Bos et al., 2012), and its implications for translational medicine (Meyer-Lindenberg et al., 2011; Striepens et al., 2011). Over the years OXT has gained the reputation of facilitating empathy and affiliation, based on early findings reporting beneficial effects of OXT on trust (Kosfeld et al., 2005), social support (Heinrichs et al., 2003), and processing social information (Hollander et al., 2007; Savaskan et al., 2008; Unkelbach et al., 2008; Hurlemann et al., 2010). This view is supported by studies showing that OXT improves cognitive empathic abilities such as mindreading (Domes et al., 2007; Bartz et al., 2010; Guastella et al., 2010) and recognizing positive emotional expressions (Marsh et al., 2010). As a result of these positive effects on social behavior, there has been considerable speculation about OXT's therapeutic potential in people with social and emotional disabilities. This prosocial view of OXT has been challenged by findings showing that the effects of OXT are strongly context-dependent (Bartz et al., 2011; Bos et al., 2012). For example, OXT has also been shown to increase envy and gloating (Shamay-Tsoory et al., 2009), defensiveness toward out-group members (De Dreu et al., 2010, 2011) and increased in-group conformity (Stallen et al., 2012). Although this ethnocentrism might be considered prosocial within one's own group, defensiveness toward an out-group is not, and extreme ethnocentrism often leads to nationalism or even racism. This paradox gives rise to two questions. First, how can the beneficial effects of OXT on empathy, trust and affiliation be compatible with its seemingly contradictory anti-social effects? Second, what implication does this have for the therapeutic potential of OXT in social and emotional neurodevelopmental conditions? With regard to the first question, we provide a brief overview of the literature aiming to understand the mechanism(s) underlying OXT's efficacy. There are two main perspectives on how OXT affects social behavior (via anxiety reduction or increasing social salience), which try to reconcile its pro- and anti-social roles, but there have been no attempts to date to integrate these into a single viewpoint. A potential third factor, reward sensitivity might aid this integration. We propose a model that unites these perspectives, providing new avenues of research into OXT's efficacy in social and emotional neurodevelopmental conditions.