People with large pupils are smarter

It is often said that the eyes are the mirror of the soul, and there is some truth in that. It has long been known that the pupils do not just dilate and contract by reacting to light, but also do so as a reaction to the mental processes that occur in Our brain.

For example, when we see something or someone that attracts us they expand more so as not to lose detail of what we have in front of us. In the same way, in simple memorization tasks, it has been seen that the pupil expands as they are maintained items in memory and they contract each time something previously memorized is recalled.

Thus, our gaze expresses more of our internal world than one might expect. However, recent research takes this idea further, by providing new evidence about the relationship between the behavior of the pupils and our psychological facet: people with larger pupils tend to be statistically smarter.

The link between pupils and fluid intelligence

The results of this research, published in the journal Cognitive Psychology

by a team of American psychologists, show that pupil diameter is correlated with higher intelligence scores. That is, groups of people with larger pupils have a greater chance to be smarter than the rest, although this rule does not have to be fulfilled in all individuals.

To carry out this research, a group of 331 volunteers was used and the size of the pupils was measured in the that these adopted their "default" size to ensure that the brightness levels did not affect the results. In addition, the psychologists took into account variables such as age, sex or the consumption of certain substances such as nicotine. Once the influence of these variables was subtracted from the equation, the correlation between pupil size and intelligence appeared.

However, the measure of intelligence whose relationship with the diameter of the pupils was recorded by this group of psychologists was not just any type of intelligence.

Specifically, it was the fluid intelligence, one of the most important components of the IQ. Basically fluid intelligence refers to the mental agility with which we find solutions to unforeseen and novel problems. Therefore, it is a type of intelligence that does not depend on our cultural level or the knowledge acquired over the years.

How do you explain this?

What causes this relationship between pupil size and higher fluid intelligence scores is, at the moment, a mystery. Of course, could be a spurious correlation, be the result of a curious chance or reflect that there is a variable between these two that causes them both at the same time. For example, it could be that people with larger-than-normal pupils come from a line of ancestors with neuroanatomical characteristics that make them more intelligent.

Another brief explanation is the one proposed by Jason S. Tsukahara, one of the researchers responsible for the study. The answer could be in a network of neurons sensitive to a substance called norepinephrine that are located in a part of the brain known as the locus coeruleus, located in the Brain stem. He notes that other research has shown a relationship between the level of activity of this group of nerve cells and the size of the pupils. At the same time, the noradrenaline makes neurons more likely to communicate with each other, creating new neural pathways that make it easier to find possible solutions and consider more options.

To clarify this, it will be necessary to repeat investigations of this type in several contexts and see if the correlation is present in each of them. In that way, from there, a theory can be developed that explains the phenomenon.