Is it me or is it you? Behavioral and electrophysiological effects of oxytocin administration on self-other integration during joint task performance

The neuropeptide oxytocin has been associated with promoting various social behaviors in humans including cooperation and trust. Surprisingly little, however, is known about the possible role of oxytocin in processes required for social interactive behavior such as joint task performance. The current study investigated whether intranasal administration of oxytocin leads to increased self-other integration using a social Simon task. A placebo-controlled double-blind between-subjects design was used. Behavioral and EEG measures were obtained from 63 healthy male volunteers who either received 24 intranasal units (IU) oxytocin or a placebo while they performed the social Simon task in an individual and a joint/social context. The behavioral results demonstrated an enhanced Simon effect in the social context after oxytocin administration. At the electrophysiological level, the stimulus-locked N2 component, reflecting response conflict, was increased in the social compared to the individual context for Go trials, but only after oxytocin administration. The P3 component, reflecting response inhibition, was increased for social compared to individual contexts, irrespective of condition. Both the behavioral and N2 findings suggest that oxytocin enhances self-other integration. While more inhibition is needed in the social context, this process seems less sensitive to changes in self-other integration. To conclude, the current study is the first to show oxytocin-induced modulations of processes that play a central role in joint task performance and thus importantly adds to our understanding of the neurocognitive mechanisms underlying the diverse social effects of oxytocin.