We investigate if the neuropeptide oxytocin (OT) known to moderate social behaviour, influences strategic decision making in social dilemmas by facilitating the integration of incentives and social cues.
Participants (N = 30) played two economic games with different incentive structures in the fMRI scanner after receiving OT or placebo (following a double blind, within-subject design). Pictures of angry or neutral faces (suggesting a threatening or safe decision environment) were displayed alongside the game matrices.
Results show that, in a coordination (or assurance) game, OT facilitates cooperation for risk averse individuals. The nucleus accumbens becomes significantly more activated than in an anti-coordination (or chicken) game. In the latter, aggression is incentivized but fatal if the partner also aggresses. Here OT significantly downregulates the amygdala and steers decisions in accordance with the valence of the facial cue: aggress when neutral; retreat otherwise.
These results are compatible with recent theories that OT facilitates heuristic decision making by modulating brain regions in the mesolimbic dopaminergic system. Through its combined influence on amygdala and nucleus accumbens, cooperative or aggressive decisions are selected in function of the best match between incentives and social cues present in the decision environment.