Figure 3.

Model parameters reveal differences in optimistic learning. The parameters of the best-fitting model reveal that children (8-9 yo) differed from the adolescent groups (12-13 yo and 16-17 yo) in their negative learning rate. (A) Children have a lower negative learning rate compared to both adolescent groups, whereas the positive learning rate is similar across all age groups (B). This means that children show a strong optimism learning bias, which diminishes with age. Additionally, children have marginally higher prior in reward belief compared to late adolescents (C). The relationship between age and optimism bias was mediated by negative learning rate (D). Mean values are shown, the c path represents the total effect of age on optimism bias and c’ represents the direct effect of age on optimism bias when controlling for the negative learning rate. The a path represents the effect on age on negative learning rate and b path represents the effect on negative learning rate on optimism bias. The ab path is the indirect effect of age on optimism bias through negative learning rate. Our findings suggest that the age-related decrease in optimism bias was primarily driven by the increase in the negative learning rate. *** p < 0.001; ** p < 0.01; * p < 0.05; t p < 0.10; yo, year-olds.