The effects of cognitive abilities and task demands on tonic and phasic pupil sizes

Samira Aminihajibashi,Thomas Hagen,Ole A Andreassen,Bruno Laeng,Thomas Espeseth

doi:10.1016/j.biopsycho.2020.107945

Abstract

Previous studies on individual differences in pupil size of healthy individuals and their relation to performance have been inconclusive. Using a novel approach, we tested the effect of general cognitive abilities and level of task performance on pretrial baseline and task-evoked pupil (TEP) sizes (N = 116) while we manipulated the level of task demands using a multiple object tracking task. Results did not reveal an effect of general cognitive abilities, estimated by working memory capacity and gF scores, on either baseline or TEP sizes. In contrast, we found an interaction in TEP sizes between level of overall MOT performance and task demands. We propose that individual differences in TEP sizes are related to state-specific level of task performance and task demands, probably in combination with other factors like age, personality traits, and state-specific level of motivation and arousal. We also suggest methodological confounds that may cause the previous inconclusive findings.

Highlights

The neurocognitive basis of individual differences in pupil size of healthy individuals has remained little studied and the results have been inconclusive
We tested the effect of general cognitive abilities and level of task performance on pretrial baseline and task-evoked pupil (TEP) sizes (N = 116) while we manipulated the level of task demands using a multiple object tracking task
We propose that individual differences in TEP sizes are related to state-specific level of task performance and task demands, probably in combination with other factors like age, personality traits, and state-specific level of motivation and arousal

Summary

Introduction

The neurocognitive basis of individual differences in pupil size of healthy individuals has remained little studied and the results have been inconclusive. In a typical pupillometry paradigm, pupillary changes are often categorized as baseline (tonic) and task-evoked (phasic) modes (for a review, see Mathôt, 2018). The ‘tonic’ or baseline pupil size is often measured while viewing a screen with a uniform or neutral background and no meaningful stimuli to attend to other than (occasionally) a fixation point. A pre-task baseline pupil size can be measured before initiating or independent of an experiment, and a separate pretrial baseline pupil size can be measured immediately before initiating each trial; effectively constituting an event-related baseline. The tonic pupil size always refers to the pretrial baseline pupil sizes. On the other hand, refers to task-evoked pupil (TEP)

Methods

Results

Discussion

Conclusion