Pupil Dilation Linked to Working Memory Capacity

Summary: Researchers have found that pupil dilation can indicate working memory levels. In one study, researchers observed that individuals whose pupils dilated more when performing memory tasks tended to have better working memory.

This relationship between pupil dilation and memory performance suggests that pupil measurements could potentially serve as noninvasive indicators of cognitive load and memory capacity. The study involved 179 undergraduate students who performed various working memory tasks while their responses were monitored.


  1. The study found a positive correlation between pupil dilation during cognitive tasks and higher working memory performance.
  2. Participants with greater pupil dilation were able to remember and process information better.
  3. This research opens the possibility of using pupil dilation as a simple, non-invasive measure of working memory in cognitive assessments.

Source: UT Arlington

Working memory is one of the brain’s executive functions, a skill that allows humans to process information without losing track of what they are doing.

In the short term, working memory allows the brain to complete an immediate task, such as loading the dishwasher. In the long run, this helps the brain decide what to store for future use, such as whether more dishwasher soap will be needed.

“What we found was that students who performed lower on the tasks had less pupil dilation,” Robison said. Credit: Neuroscience News

Researchers at the University of Texas at Arlington know that working memory varies widely among individuals, but they don’t know exactly why.

To better understand, Matthew Robison, assistant professor of psychology, and doctoral student Lauren D. Garner conducted an experiment to see if studying a person’s pupils (the center of their eyes) was a good indicator of memory. work.

Normally, a person’s pupils naturally widen (or dilate) in dimly lit environments to allow more light to enter the eyes.

However, in their new study published in Attention, perception and psychophysicsresearchers reported that a person’s pupils also dilate when they concentrate on tasks.

In particular, they found that the more a person’s eyes dilated during the task, the better they performed on tests measuring their working memory.

“What we found was that students who performed lower on the tasks had less pupil dilation,” Robison said.

“For higher-performing participants, their pupil dilations were larger overall and individuals were more perceptive about the information they were asked to remember.”

For the study, he and Garner recruited 179 undergraduate students at UT Arlington. Participants completed several working memory tasks in which they were presented with information and then asked to remember it for a few seconds.

During the tasks, participants had their pupils continuously measured using an eye-tracker, similar to that used by optometrists during eye exams.

“We found that people who paid more intense and consistent attention, as measured by the increased dilation of their pupils, performed better on memory tasks,” Robison said.

“Importantly, we found that high-achieving students also showed greater student sensitivity than low-achieving participants. This is exciting research because it adds another valuable piece of the puzzle to our understanding of why working memory varies across individuals.

About this latest research on memory and visual neuroscience

Author: Katherine Egan Bennett
Source: UT Arlington
Contact: Katherine Egan Bennett – UT Arlington
Picture: Image is credited to Neuroscience News

Original research: Closed access.
“Pupillary correlates of individual differences in n-back task performance” by Matthew K. Robison et al. Attention, perception and psychophysics


Pupillary correlates of individual differences in n-back task performance

We used pupillometry during a two-feedback task to examine individual differences in intensity and consistency of attention and their relative role in a working memory task.

We used sensitivity, or the ability to distinguish between targets (2-way matches) and non-targets, as a measure of task performance; task-evoked pupillary responses (TEPR) as a measure of attentional intensity; and students’ pretrial intraindividual variability as a measure of attentional coherence.

TEPRs were higher on target trials than on nontarget trials, although there was no difference in TEPR magnitude when participants responded correctly or incorrectly to targets.

Importantly, this effect interacted with performance: High performers showed greater separation in their TEPRs between targets and nontargets, whereas there was little difference for low performers.

Furthermore, in the regression analysis, higher TEPRs on target trials predicted better performance, whereas higher TEPRs on non-target trials predicted worse performance.

Sensitivity was positively correlated with pretest mean pupil diameter and negatively correlated with intraindividual variability in pretest pupil diameter.

Overall, we found evidence that attentional intensity (TEPR) and consistency (pretrial student variation) predict performance on a not-return working memory task.

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