Fig. 5.

Regression results on trialwise changes in pupil diameter. (A) In both age groups, positive betas of the trialwise pupil prediction show that pupil diameter is larger on trials with more model updating (red and orange lines indicate time points of a reliable [p < 0.05] positive effect for older and younger adults, respectively). This effect is stronger in younger adults (time points of a reliable age differences indicated by black line). (B) Trialwise changes in surprise were not related to changes in pupil diameter. Regression lines indicate means of betas across individual regressions within age groups; shaded areas indicate SEs across individuals within age groups. Regressions calculate betas per sample point, time points of reliable effects are determined based on permutation tests in time window 1–2.5 seconds after feedback onset. (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)