Abstract
A large body of animal research suggests that oxytocin is crucial in the formation of male-female sexual relationships. In humans, several experimental studies have suggested that oxytocin has a role in everyday interactions; however, it is not clear whether oxytocin also plays a role in the formation of human romantic relationships. Thus, Experiments 1 and 2 explored whether oxytocin can promote romantic relationships between two human strangers. Experiment 1 looked at whether oxytocin may do so by: (i) positively biasing evaluation, (ii) improving memory, or (iii) creating a preference for an opposite-gendered stranger. This was assessed by introducing seventy-six undergraduate students to the stranger via video-clip, with participants having taken either oxytocin or placebo. There was no strong evidence that oxytocin could assist in evaluation, memory, or partner preference: if any effects were found at all, they were stranger-specific, participant-specific, or were limited to just one type of setting. Experiment 2 examined whether oxytocin could increase approach behaviours towards an opposite-gendered stranger. One hundred and four undergraduate students were paired up with another participant of the opposite gender, and introduced to each other in a face-to-face conversation. Again, there was no evidence that oxytocin could facilitate social approach, defined as the simultaneous increase in conversational intimacy, eye-contact, and physical proximity. Further, across both Experiments 1 and 2, there was some suggestion that oxytocin could even cause participants to view a stranger negatively. These data suggest that oxytocin has at best a modest influence on human relationship formation. Such a conclusion has implications for the clinical utility of oxytocin, as well as for translational research comparing animal and human relationships.