Pupil dilation indicates cognitive effort on a distinct 900 ms timescale

Evidence

Pupil dilation reflects next to adaptations to changes in luminance or lightness, occurring within the timescale of 200–500 ms, also a slower evolving response to mental effort, in the timescale of about 900 ms (Hoeks and Levelt 1993 ). — Dijk, Pim van, Physiology, Psychoacoustics and…, 3958

Categorization

• DEFINE: Defines pupil dilation as a two-component signal with separable timescales, distinguishing effort responses from light reflexes.