Pupils as an Indicator of Intelligence

Eyes are the windows to the soul and they have mysterious abilities that we can not even imagine. The eyes are not just a sensory organ that responds to light and provides sight. They have even more different applications. Recently, scientists discovered that eyes are actually an indication of intelligence. 

Research conducted at the Georgia Institute of Technology suggests that pupil size is an indicator of intelligence. Higher intelligence, attention, and memory are linked with bigger pupils.  Researchers have come to this hypothesis while studying differences in the amount of mental effort people used to complete memory tasks. They tested Daniel Kahneman’s technique and discovered the relationship between pupil size and intelligence. They then decided to conduct a full study to fully validate this theory. Researchers in the university published an article in Scientific American and explained the procedure and their observations as follows, “Intrigued, we conducted several large-scale studies in which we recruited more than 500 people aged 18 to 35 from the Atlanta community. We measured participants’ pupil size using an eye tracker, a device that captures the reflection of light off the pupil and cornea using a high-powered camera and computer. We measured participants’ pupils at rest while they stared at a blank computer screen for up to four minutes. All the while, the eye tracker was recording. Using the tracker, we then calculated each participant’s average pupil size. In the next part of the experiment, participants completed a series of cognitive tests designed to measure “fluid intelligence,” the capacity to reason through new problems, “working memory capacity,” the ability to remember information over a period of time, and “attention control,” the ability to focus attention amid distractions and interference”. The results confirmed the researchers’ hypothesis: baseline pupil size is strongly correlated with great fluid intelligence, attention, and working memory capacity. However, pupil size is negatively correlated with age. Younger participants generally have larger pupil sizes. 

But what affects these relationships? First of all pupil size is related to activity in the locus coeruleus. As stated, “One hypothesis is that people who have larger pupils at rest have greater regulation of activity by the locus coeruleus, which benefits cognitive performance and resting-state brain function”. 

Even tough these amazing scientific discoveries, additional research is still required to fully understand the relationship.


[1] “Is Baseline Pupil Size Related to Cognitive Ability? Yes (under Proper Lighting Conditions).” ScienceDirect, 1 June 2021, http://www.sciencedirect.com/science/article/abs/pii/S0010027721000627##.

[2] Powell, Selina. “Pupil Size Linked to IQ.” Association of Optometrists, 19 June 2021, http://www.aop.org.uk/ot/science-and-vision/research/2021/06/19/pupil-size-linked-to-iq.

[3] Tsukahara, Jason Alexander S. Burgoyne. “Pupil Size Is a Marker of Intelligence.” Scientific American, 2 June 2021, http://www.scientificamerican.com/article/pupil-size-is-a-marker-of-intelligence.

[4] Wikipedia contributors. “Daniel Kahneman.” Wikipedia, 14 Sept. 2021, en.wikipedia.org/wiki/Daniel_Kahneman.

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