Figure 3. Assessing models of learning.

(a) Random-Effects Bayesian Model Comparison confirmed that the Hierarchical Gaussian Filter (HGF) outperformed fixed-learning-rate models (Rescorla–Wagner) and variable-learning-rate non-Bayesian models (Sutton K1). (b) Life stress was assessed with a Perceived Stress Scale³⁸. Life stress scores were correlated with the metavolatility parameter (ϑ) in the HGF, suggesting that more stressed individuals believe the world to be less stable (n=41; Spearman ρ=0.38, P=0.014).