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. 2024 May 10;7(1):41.
doi: 10.5334/joc.365. eCollection 2024.

Baseline Pupil Size Seems Unrelated to Fluid Intelligence, Working Memory Capacity, and Attentional Control

Veera Ruuskanen  1 , Thomas Hagen  2 , Thomas Espeseth  2   3 , Sebastiaan Mathôt  1
Affiliations

Baseline Pupil Size Seems Unrelated to Fluid Intelligence, Working Memory Capacity, and Attentional Control

Veera Ruuskanen et al. J Cogn. .

Abstract

Over the past few years, several studies have explored the relationship between resting-state baseline pupil size and cognitive abilities, including fluid intelligence, working memory capacity, and attentional control. However, the results have been inconsistent. Here we present the findings from two experiments designed to replicate and expand previous research, with the aim of clarifying previous mixed findings. In both experiments, we measured baseline pupil size while participants were not engaged in any tasks, and assessed fluid intelligence using a matrix task. In one experiment we also measured working memory capacity (letter-number-sequencing task) and attentional control (attentional-capture task). We controlled for several personal and demographic variables known to influence pupil size, such as age and nicotine consumption. Our analyses revealed no relationship between resting-state pupil size (average or variability) and any of the measured constructs, neither before nor after controlling for confounding variables. Taken together, our results suggest that any relationship between resting-state pupil size and cognitive abilities is likely to be weak or non-existent.

Keywords: Baseline pupil size; attentional control; fluid intelligence; working memory capacity.

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Conflict of interest statement

The authors have no competing interests to declare.

Figures

Grey boxes with text inside
Figure 1
An overview of the experimental procedure in Groningen.
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Figure 2
The three tasks completed by participants in Groningen. A) An example of a trial of the matrix task used to assess fluid intelligence. B) An example of a trial of the Letter-Number-Sequencing task (LNS) used to assess working memory capacity (WMC). C) An example of the attentional-capture task used to assess attentional control. Note: In the actual task the background was dark and the line segments in the shapes were white. The colors are reversed here for illustration purposes.
A blue histogram displaying approximately normally distributed data
Figure 3
Distribution of resting-state pupil size in mm, as recorded from the sample collected in Oslo (N = 122).
Two scatterplots side-by-side
Figure 4
The relationship between baseline pupil size and fluid intelligence (as assessed with a matrix task). A) Average pupil size and fluid intelligence. B) Variability in pupil size and fluid intelligence.
A blue and green box plot side-by-side
Figure 5
Distribution of pupil sizes across levels of nicotine consumption in the full sample (“no” indicating no nicotine consumption on the day of the experiment (N = 197) and “yes” indicating nicotine consumed on the day of the experiment (N = 16)).
Two scatterplots side-by-side
Figure 6
The relationship between baseline pupil size and working memory capacity (as assessed with a Letter-Number-Sequencing task). A) Average pupil size and WMC. B) Variability in pupil size and WMC.
Two scatterplots side-by-side
Figure 7
The relationship between baseline pupil size and attentional control (as assessed with an attentional-capture task. A) Average pupil size and attentional control. B) Variability in pupil size and attentional control.
A purple and orange box plot side-by-side
Figure 8
Distribution of pupil sizes across levels of nicotine consumption in the Groningen sample (“no” indicating no nicotine consumption on the day of the experiment (N = 94) and “yes” indicating nicotine consumed on the day of the experiment (N = 8)).
See this image and copyright information in PMC

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