Pupil dilation as an index of effort in cognitive control tasks: A review.
Level 5 - mechanism / opinion, no new human data
Narrative review synthesizing literature without a systematic review protocol or meta-analysis
PubMed 29435963 · doi:10.3758/s13423-018-1432-y
What was done
The authors reviewed recent literature examining task-evoked pupil dilation during cognitive control tasks, specifically focusing on three domains: working memory updating, task switching, and response inhibition. They evaluated the feasibility of using pupil dilation as an index of exerted mental effort rather than task demand or difficulty.
What was found
The abstract reports no numerical values or effect sizes. Qualitatively, across updating, switching, and inhibition tasks, increases in task demands typically lead to increases in pupil dilation. Relationships between pupil dilation and behavioral performance diverge across studies, which the authors suggest can be explained by an effort-based account.
Why it matters
This paper organizes pupillometric findings across core executive functions, proposing a theoretical framework that treats pupil dilation as a marker of cognitive effort exertion rather than objective task difficulty.
Limits
As a narrative review, it lacks a systematic search strategy, defined inclusion criteria, risk-of-bias evaluation, or quantitative meta-analysis. The abstract provides no sample sizes or count of reviewed studies. Key physiological and physical confounders of pupil diameter (such as baseline arousal, light reflex, and gaze position) are not addressed in the abstract.
Cited by
- supports Cognitive load and mental effort can be indexed and measured by changes in pupil diameter.
- supports Pupil diameter increases in response to increased cognitive load, heightened arousal, and higher levels of alertness.