Fig. 4: The model explains puzzling issues in Pavlovian learning.
From: A model for learning based on the joint estimation of stochasticity and volatility
a–d Pearce and Hall’s conditioned suppression experiment. The design of experiment51, in which they found that the omission group show higher speed of learning than the control group (a). b Median learning rate over the first trial of the retraining. The learning rate is larger for the omission group due to increases of volatility (c), while stochasticity is similar for both groups (d). The model explains partial reinforcement extinction effects (e–h). e The partial reinforcement experiment consists of a partial condition in which a light cue if followed by reward on 50% of trials and a full condition in which the cue is always followed by the reward. f Learning rate over the first trial of retraining has been plotted. Similar to empirical data, the model predicts that the learning rate is larger in the full condition, because partial reinforcements have relatively small effects on volatility (g), but it considerably increases stochasticity (h). Errorbars reflect standard error of the mean over 40,000 simulations and are too small to be visible. See Supplementary Figs. 4 and 5 for empirical data and corresponding response probability by the model. Source data are provided as Source Data file.
