Individual differences in resting-state pupil size: Evidence for association between working memory capacity and pupil size variability

https://doi.org/10.1016/j.ijpsycho.2019.03.007Get rights and content
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Highlights

  • First evidence for a positive relation between working memory capacity (WMC) and resting-state pupil size variability

  • The average resting - state pupil size did not differ between individuals with high and low level of WMC.

  • These results are informative on the role of noradrenergic activity and arousal on WMC.

Abstract

Dynamic non-luminance-mediated changes in pupil diameter have frequently been shown to be a reliable index for the level of arousal, mental effort, and activity in the locus coeruleus, the brainstem's noradrenergic arousal center. While pupillometry has most commonly been used to assess the level of arousal in particular psychological states or the level of engagement in cognitive tasks, some recent studies have found a relationship between average resting-state (i.e. baseline) pupil sizes and individuals' working memory capacity (WMC), indicating that individuals with higher WMC on average have larger pupils than individuals with relatively lower WMC. In the present study, we measured pupil size continuously in 212 participants during rest (i.e. while fixating) and estimated WMC in all participants by administering the Letter-Number Sequencing (LNS) task from WAIS-III. We were unable to replicate the relation between average pupil size and WMC. However, the novel finding was that higher WMC was associated with higher variability in resting-state pupil size. The present results are relevant for the current debate on the role of noradrenergic activity on working memory capacity.

Keywords

Resting-state
Pupil size variability
Working memory capacity
Individual differences
Locus coeruleus-norepinephrine system

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