People with large pupils tend to be 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 are not limited to dilate and contract 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 dilate more so as not to lose detail of what we have before us. In the same way, in simple memorization tasks, it has been seen that the pupil expands as elements are kept in the memory and contract each time something previously memorized is remembered.
Thus, our gaze expresses more of our inner world than we would expect. However, a recent investigation takes this idea further, to provide new evidence about the relationship between the behavior of the pupils and our psychological facet: people with larger pupils tend to be smarter, in statistical terms .
The link between the pupils and fluid intelligence
The results of this research, published in the journal Cognitive Psychology by a team of American psychologists, show that the diameter of the pupils is correlated with higher intelligence scores . That is, groups of people who have larger pupils have a greater chance of being 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 in which they adopted their "default" size was measured to ensure that the luminosity levels did not affect the results. In addition, 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 the size of the pupils and the intelligence appeared.
However, the intelligence measure whose relation to the diameter of the pupils was recorded by this group of psychologists was not any kind of intelligence.
Specifically, it was about 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 is this explained?
What causes this relationship between the size of the pupils and the higher scores in fluid intelligence is, for the moment, a mystery. Of course, it could be a spurious correlation , be the result of a curious chance or reflect that there is a variable between these two that causes both at once. For example, it could be that people with larger pupils than normal come from a line of ancestors with neuroanatomical characteristics that make them smarter.
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 noradrenaline that are located in a part of the brain known as locus coeruleus, located in the brain stem. He points out that other investigations have shown a relationship between the level of activity of this group of nerve cells and the size of the pupils. At the same time, norepinephrine makes neurons more likely to communicate with each other, creating new neuronal 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 one of them. In that way, from there, you can start to develop a theory that explains the phenomenon .