Taste uncertainty explains developmental effects on susceptibility to peer influence in adolescence

Adolescence is a time of pronounced cognitive, neural, and social change. Adolescents are prone to social influence from peers, with implications for development, both adaptive and maladaptive. However, the underlying cognitive mechanisms of this influence, as well as their neuro-developmental correlates and real-life social consequences are poorly understood. Here, we replicate a cross-sectional effect of more susceptibility to peer influence in adolescents in a large dataset of 14 to 24 years old. Crucially, we extend this finding by adopting a longitudinal perspective, showing that a within-person susceptibility to social influence decreases over a 1.5 years follow-up time period. Exploiting this longitudinal design, we show that susceptibility to social influences at baseline predicts an improvement in peer relations over the follow-up period. Using a Bayesian computational model, we provide novel mechanistic insight into these effects, showing that in younger adolescents a greater tendency to adopt others’ preferences arises out of a higher uncertainty about their own preferences (a phenomenon called ‘taste uncertainty’). This taste uncertainty decreases over time and, in turn, leads to a reduced susceptibility of one’s own behaviour to an influence from others’. Neuro-developmentally, we show that a measure of myelination within medial prefrontal cortex, estimated at baseline, predicts a developmental decrease in taste uncertainty at follow up. Thus, using computational and neural evidence, we reveal adaptive mechanisms underpinning susceptibility to social influence during adolescence.