Navigating a varying reward environment in childhood and adolescence.

Optimal reward learning requires individuals to adjust their learning rates - the extent to which new information replaces old. Learning rates should be higher in volatile environments, where new information is more salient, and lower in stable environments, where the longer-term history of outcomes is more predictive. It is not known, however, whether this adjustment in learning rates changes with age or is associated with better mental health and social functioning. We administered a child-friendly probabilistic reinforcement learning task with both fixed and fluctuating reward schedules to 121 participants aged 8-16 years. Adjustment of learning rates across childhood and adolescence to suit the levels of uncertainty in the environment did not differ by age, nor was it associated with better mental health and social functioning. Instead we found that learning rates for worse-than-expected outcomes generally decreased with age, temperature increased with age and higher learning rates, specifically during positive stable environments, were associated with greater self-reported prosocial behaviour. Our results highlight the exaggerated impact of negative feedback on children and suggest an increase in exploratory behaviour between childhood and adolescence.