People say you can tell a lot about a person just by looking into their eyes. Whether they're tired, happy, or even turned on – the eyes are a dead giveaway.
Our pupils in particular are perhaps the most visibly active parts of our eyes. They constrict and dilate depending on a whole host of environmental factors and stimuli. Hell, even the FBI looks at pupil dilation to determine whether a suspect is lying during an interrogation.
But a recent study has found that pupils, more specifically their size, may be more than just indicators of your emotional state.
Scientists at the Georgia Institute of Technology (Georgia Tech) believe that pupil size can determine a person's level of intelligence.
Or rather, they've found that baseline pupil size is "closely related" to differences in intelligence among individuals.
According to the study, published on Science Direct, people with larger pupils are more likely to have higher intelligence. The scientists used a series of tests on more than 500 18-to-35-year-olds in the Atlanta area, divided into three categories: Reasoning, attention, and memory. They're all essentially designed to test the cognition of each individual with regard to external factors in their surroundings.
IMAGE: Gayatri Malhotra / Unsplash
Throughout all three studies, the group of scientists found that the difference in baseline pupil size among participants who scored the highest and those who scored lowest was discernible to the human eye. No special equipment needed.
"When we discovered a relationship between baseline pupil size and intelligence, we weren’t sure if it was real or what it meant," the scientists explained in Scientific American.
All conditions in the tests had to be perfect.
Using special eye trackers in the form of a high-powered camera and computer, the scientists were able to capture the reflection of light off the pupil and cornea. During this process, participants were told to stare at a blank computer screen for up to four minutes. This allowed scientists to record their baseline pupil size – essentially the original or default size barring any stimuli.
Because pupils tend to respond to bright light (by constricting), the scientists also made sure to keep the lab environment dim to preserve true results.
In the "attention control" test, for example, participants were told not to pay any attention to a blinking asterisk (*) on one side of the computer screen. Instead, they needed to quickly look at the opposite side of the screen and identify the letter that appeared. The letter would also disappear very quickly.
IMAGE: JD X / Unsplash
Even a quick glance at the blinking asterisk might result with the participant not being able to identify the letter that appeared on the other side of the screen. Pesky asterisk messing with peripheral vision!
The test found that people with a larger baseline pupil size were more likely able to keep their focus on the letters, as opposed to the blinking asterisks. Similar results were achieved in the reasoning and memory tests as well.
Interestingly, the study also found that pupil size had a negative correlation with age, meaning that older participants tended to have smaller, more constricted pupils.
What's the logic that drives the link between pupil size and intelligence in the first place?
Pupil size is more specifically linked to the locus coeruleus, which is a part of the brain that's responsible for producing noradrenaline, a hormone that regulates processes like perception, attention, learning, and memory.
Alzheimer's disease and attention deficit hyperactivity disorder (ADHD) have both been attributed to a dysfunctional locus coerueleus. So this part of the brain definitely plays an extremely important role in basic human function.
IMAGE: Fakurian Design / Unsplash
However, the study has been met with a lot of contention from fellow scientists. In fact, at the very top of their publication, the scientists make it known that "other researchers have not been able to replicate our findings", pointing out that external parties only studied working memory capacity, not fluid intelligence (reasoning).
The group of researchers also pointed out that external studies had flawed methodologies, namely small baseline pupil size values "down to the physiological minimum".
Make of that what you will.
So, do you possess high intelligence, aka big pupils?
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Cover image sourced from Courtney Cook / Unsplash and Marc Schulte / Unsplash.
