Fig. 4: Exp. 2—ALE patients are less sensitive to changes in reward under uncertainty.

a, Patients (n = 19) and healthy controls (n = 19) adjusted their decisions according to the reward and uncertainty on offer. The influence of reward on offer acceptance was blunted in ALE patients when compared with controls (shallower reward slope). Level 1 indicates lowest reward/uncertainty level on offer. b, Controls accepted more of the high-value offers (blue region) than hippocampal patients did. c, Investigation of the group effect using an L_gMM revealed that patients had significantly lower sensitivity to reward than controls but did not significantly differ in their sensitivity to uncertainty (ALE × reward: β = −0.983; t₃₇₄₈ = −3.58; P < 0.001; 95% CI, (−1.52, −0.44)). It also showed that the impact of uncertainty on decision-making was more significant than the impact of reward (histogram on the corner). d, Lower sensitivity to reward, but not to uncertainty, in the passive task is associated with lower sensitivity to sampling cost in the active sampling task (Exp. 1) driving group differences in the number of samples collected. The colour scale indicates the contribution of each data point to the model. The blue dots represent controls and are added for visual comparison. The error bars and shading in a show ±s.e.m. The solid line and shading in d show the regression line and 95% CI. See Supplementary Table 8 for the full statistical details.