People with larger pupil sizes are more intelligent, study finds

A research by the Georgia Institute of Technology in the United States have found that pupil size can tell about a person’s intelligence. The study was published in the June issue of Cognition.

Jason Tsukahara and Randall Engle, the scientists who performed the study, wrote along with Alexander Burgoyne in a Scientific American article.

“We found that the difference in baseline pupil size between people who scored the highest on the cognitive tests and those who scored the lowest was large enough to be detected by the unaided eye.”

Scientists conducted large-scale studies on over 500 people between the age of 18 and 35.

They asked participants to stare at a blank computer screen in dim laboratory light conditions.

Then, the researchers measured the pupil size of the participants using an eye tracker – a high-powered camera connected to a computer to accurately capture the cornea and pupil. Scientists calculated each person’s average pupil size using the eye tracker.

Afterward, the participants had to perform some tasks that were designed to measure their “fluid intelligence” – an ability to reason through and solve new problems, “attention control” – the ability to maintain focus amid distractions, and “working memory capacity” – the ability to store information over a required period of time.

Scientists found that people with larger pupil sizes had higher fluid intelligence and attention control. They also had higher memory capacity but the difference was not as much compared to that in the case of fluid intelligence and attention control.

The size of pupils tells how much regulation, organisation, and coordination among different parts of the brain is happening. If this coordination is better, a person can accomplish more challenging tasks leading to better brain performance or cognitive ability which is reflected in a person’s pupil size even while resting.