Serotonin and aversive processing in affective and social decision-making

•Accumulating evidence links serotonin function with aversive processing.•Serotonin modulates aversive processing in both non-social and social decision contexts.•In affective decisions serotonin links aversive predictions with behavioral inhibition.•In social contexts serotonin modulates the valuation of decisions affecting others.•Future work could aim to integrate serotonin's roles in behavioral inhibition and valuation.

The effects of the neuromodulator serotonin on affect and behavior are so diverse and wide-ranging that characterizing its function has faced substantial challenges. Here we review recent work investigating how serotonin shapes affective and social decision-making in humans, focusing in particular on serotonin's influence on aversive processing. We consider the evidence that serotonin plays a key role in linking so-called Pavlovian aversive predictions with behavioral inhibition, a proposal derived from computational models of value-based decision-making. We evaluate the extent to which a core mechanism connecting serotonin with Pavlovian inhibition can explain diverse effects of serotonin on affective and social decision-making and highlight critical questions for future research.