<p>Out-of-sample validation of estimated parameters on the held-out test phase (HC group).</p>

<p>Test phase choices were predicted from end-of-training RL values obtained from each participant’s learning phase, with no parameters fit to test data and an identical softmax rule applied to both models, so predictions differed only in the learned values each implied (see Methods). <b>(A)</b> Probability of choosing the higher-valued stimulus by within-participant value-difference tertile, for empirical data (black), PADDL (blue), and the choice-only softmax model (green).

The choice-only model overpredicts accuracy, exceeding the empirical estimates at the medium and high bins, whereas PADDL tracks the empirical curve closely. <b>(B)</b> Psychometric function of choosing the right-hand stimulus against the signed value difference (). The choice-only curve is too steep through indifference, the signature of over-separated learned values, while PADDL matches the empirical slope. Shaded bands denote 94% HDI.</p>