Model performance. A: Model comparison. Group-level log Bayes factors δiBIC for each model relative to model ‘Belief’ across all datasets. A difference ≥10 in this measure is strong evidence for the model with the lower score. B: The parameter γ in the model largely captures the probability with which participants made a correct choice. Note that, by design of the task, this explicitly captures the effect of symmetric instructions and perceptual difficulties, rather than the asymmetric effect of rewards.