Oxytocin is known to promote social affiliation. The mechanism by which this occurs is unknown, but it may involve changes in social information processing. In a placebo-controlled study, we examined the influence of intranasal oxytocin on effortful and automatic attentional shifting in 57 participants using a spatial cueing task with emotional and neutral faces. For effortful processing, oxytocin decreased the speed of shifting attention to sad faces presented for 750 ms and facilitated disengagement from right hemifield sad and angry faces presented for 200 ms. For automatic processing, symptoms of depression moderated the relationship between drug and disengagement. Oxytocin attenuated an attentional bias to masked angry faces on disengagement trials in persons with high depression scores. Oxytocin's influence on social behavior may occur, in part, by eliciting flexible attentional shifting in the early stages of information processing.

The administration of oxytocin improved participants' self-perceptions of their personality, at least for certain traits important for social affiliation. Increased positive self-referential processing may be one mechanism by which oxytocin promotes positive social behaviors.

Oxytocin facilitates pro-social behaviour and is proposed as a regulatory factor controlling stress reactivity. Previous research on oxytocin and stress has focused on achievement-related stressors among male participants. The aims of the study were to (1) examine the influence of oxytocin on the affective and cortisol response to the Yale Interpersonal Stressor (YIPS), a live social rejection paradigm, and (2) to replicate the finding that women exhibit a greater cortisol response to interpersonal stress than men (Stroud et al. 2002). Sex differences in stress responses: Social rejection versus achievement stress. Biol Psychiat 53:318-327. Ninety-six undergraduate students underwent the YIPS, where participants were excluded from two separate conversations by two same-sex confederates. Salivary cortisol concentrations and mood were repeatedly measured throughout the study. Participants were administered, in a double-blind design, a single dose of intranasal oxytocin (24 IU) or placebo prior to beginning the YIPS. The YIPS elicited a significant negative mood response that was more pronounced in females than in males. However, no significant cortisol response to the stressor and no sex difference in cortisol reactivity were observed. A significant effect of drug condition on cortisol levels was observed. Participants who were administered oxytocin exhibited a decrease in cortisol levels, relative to placebo, during the YIPS, F (4, 184)=4.50, p<0.05. The study failed to replicate the sex difference in the cortisol response to interpersonal stress reported by Stroud et al. (2002). Intranasal oxytocin, however, appeared to reduce cortisol concentrations during an interpersonal challenge.

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Although the findings do not support the stress generation theory, they suggest that elevated levels of episodic and chronic stress may be important markers of risk for affective disorders in high-risk participants.