Oxytocin was originally studied as the "milk let-down factor," i.e., a hormone that was necessary for breast-feeding. However, there is increasing evidence that this hormone also plays an important role in social bonding and maternal behaviors.
A new study scheduled for publication in the August 1st issue of Biological Psychiatry now shows that one way oxytocin promotes social affiliation in humans is by enhancing the encoding of positive social memories.
Adam J. Guastella, Ph.D. and his colleagues sought to evaluate the effects of oxytocin on the encoding and recognition of faces in humans. They recruited healthy male volunteers and in a double-blind, randomized design, administered either oxytocin or a placebo. They then presented a series of happy, angry and neutral human faces to the volunteers on a computer screen. Participants returned the following day where they were presented with a collection of faces and asked to distinguish the new faces from ones that they saw on the prior day. The results revealed that those who received oxytocin were more likely to remember the happy faces they had seen previously, more so than the angry and neutral faces.