Fig. 3.

Effect of stress on model-based vs. model-free value weights, as determined by the computational model. (A) Individual subjects’ model-based value weights, plotted separately for subjects in the control and stress conditions. There was a significant negative effect of cortisol delta on expression of model-based learning, indicating cortisol change diminished its behavioral expression. (B) Model-free contribution to behavior. Note that there was no significant effect of cortisol change on expression of model-free choice, indicating that expression of model-free contribution is spared. Regression lines are computed from the population-level estimate of the log-linear effect of stress on model-based weight. Dashed gray lines indicate 2 SEs.