Fine-grained versus categorical: Pupil size differentiates between strategies for spatial working memory performance

Area of Science:

• Cognitive Neuroscience
• Psychology

Background:

• Pupillometry offers high temporal resolution for studying working memory.
• Previous research linked pupil size to working memory load, but not representation quality.

Purpose of the Study:

• Investigate if pupil size reflects the quality of spatial working memory representations.
• Examine the relationship between pupil dilation, response precision, and categorical representation.

Main Methods:

• A spatial working memory task with 30 participants.
• Continuous recording of pupil dilation during encoding, maintenance, and response.
• High-precision joystick used to measure spatial accuracy.

Main Results:

• Pupil dilation during early encoding correlated with response precision.
• Later pupil dilation predicted shifts toward prototypical locations, indicating categorical representation.
• Individual differences showed that reliance on categories was linked to precision errors.

Conclusions:

• Pupil size variations reflect the quality of spatial working memory representations.
• Suggests compensatory strategies where loss of precise information increases reliance on categories.