Effects of oxytocin on women's aggression depend on state anxiety

Research on oxytocin (OT) indicates that it has stress reducing effects. This leads to opposing predictions of decreased and increased aggression which we examine in this study. Following completion of a state anxiety measure and administration of OT or a placebo, female participants took part in a competitive aggression game (PSAP) for a monetary prize which, if won, would be paid to a loved one. In the game, three options were available: participants could earn points; attack their opponent by deducting points; and defend themselves against point deduction by their opponent. There was no main effect of OT on these responses, however there was an interaction with state anxiety. In the placebo condition, women higher in state anxiety showed a significantly higher ratio of Attack-to-Earn responses than low anxiety women. Under oxytocin, there was a significant reduction in their Attack:Earn ratio resulting in no significant difference between high and low state anxiety groups. There was a similar trend for the Defend:Earn ratio. The reduction of reactive aggression in state anxious women supports the view that OT may decrease negative behavior and increase constructive behavior even under conditions of provocation.