Pupil dilation as a physiological marker of metacognitive processes.

Metacognition plays a crucial role in learning and decision-making across the life span. However, the neurophysiological substrates of metacognitive processes remain poorly understood. Recent evidence suggests that activity in the locus coeruleus-noradrenaline system may subserve post-response monitoring processes. In the present study we investigated whether pupil dilation, as an indirect and non-exclusive measure of noradrenergic activation, allows for characterizing metacognitive monitoring across different tasks and cognitive domains. Sixty young adults performed multiple experimental tasks during eye-tracking recordings. A battery of tasks testing mental rotation, visual perception and working memory was employed to test the association between pupil dilation and confidence judgments across multiple cognitive domains. In addition, an adapted version of the error awareness task was used to replicate the findings on the relationship between pupil size and error awareness. Pupil dilation measured during confidence judgments was found to be greater for high confidence judgments in mental rotation, visual perception and working memory tasks. In line with previous evidence, it was found that pupil size was larger after aware errors as compared to unaware errors. The study findings suggest that pupil dilation can be used as a robust marker of metacognitive processes and that noradrenergic function may contribute to metacognition in a domain-general fashion.