The influence of sensory noise, confidence judgments, and accuracy on pupil responses and associated behavioural adjustments in young and older people

We investigated the association between pupil responses, decision confidence and decision accuracy, their relationship with behavioural adjustments important for optimal task performance, and if these were altered in older adults.

We tested young and older adults, including men and women, with a dot motion direction discrimination task, while measuring task-related pupil responses. Feedback was provided after each trial. Participants were instructed to report perceived motion direction and simultaneously their decision confidence.

Older adults were overconfident in the presence of high sensory noise and in incorrect trials. Young people’s pupil responses reflected performance lapses. This effect was reduced in older people that showed blunted pupil responses to lapses and to negative feedback. Low confidence, errors, and larger pre-feedback pupil responses were associated with slower reaction time on the subsequent trial. The effects of errors and pupil were stronger in the older group.

In conclusion, older people’s blunted pupil responses following lapses suggest reduced awareness of their own abilities and internal brain state and might impair adjustment of behaviour for optimal performance.