Task-evoked pupillary responses track effort exertion: Evidence from task-switching

Area of Science:

• Cognitive Psychology
• Neuroscience
• Psychophysiology

Background:

• Quantifying cognitive effort is crucial for understanding goal-directed behavior regulation.
• Task-evoked pupillary responses (TEPRs) are a potential psychophysiological index of cognitive effort, but distinguishing effort from task load is challenging.

Purpose of the Study:

• To disentangle whether pupil diameter reflects cognitive effort exertion or task load.
• To investigate the influence of executive function and monetary incentives on TEPRs and their relationship with cognitive effort.

Main Methods:

• Utilized a task-switching paradigm with monetary incentives.
• Measured individual differences in executive function using Stroop interference.
• Analyzed task-evoked pupillary responses (TEPRs) in relation to task demands and incentives.

Main Results:

• Larger TEPRs were observed for task switches compared to repetitions, aligning with both effort and demand accounts.
• Baseline phasic pupillary responses predicted smaller switch costs, and reward-induced pupillary changes predicted reward-induced switch cost reductions.
• The relationship between pupil diameter and effort was modulated by individual differences in Stroop interference costs.

Conclusions:

• Findings support an effort-based account of TEPRs.
• Pupillometry is a viable and sensitive index for measuring cognitive effort in psychophysiological research.