A team of scientists at Georgia Institute of Technology (GAIT) has studied the link between pupil size and intelligence in 500 Atlanta volunteers between the ages of 18 and 35. They were asked to take tests on thinking, attention and memory. It turned out that pupil dilation shows not only excitement or exhaustion, but can be a marker of individual differences in intelligence. The larger the pupils, the higher the intelligence, experts say in a study published in the journal Cognition.
Differences in baseline pupil size between those with the highest and lowest intelligence test scores could be seen with the naked eye. And this may be due to the fact that people with larger pupils have a better level of brain activity in an area related to intelligence and memory. Researchers also noted a negative correlation between pupil size and age: older volunteers tended to have smaller and more constricted pupils.
Pupil size is related to an area known as locus coeruleus, a blue spot in the upper brainstem that spreads through the rest of the brain via neural connections. It releases a chemical that functions as a hormone in the brain and body, and as a neurotransmitter acts for regular processes like perception, attention and memory. The same area also plays an important role in helping distant areas of the brain work together to perform complex tasks.
Researchers formulated the outcome of the study as follows: people with large pupils have better regulation of processes in this area of the brain, which improves its cognitive and functional abilities.
Previously, Scottish scientists have found the source of high intelligence in children. A team of researchers from the University of Edinburgh (Scotland) conducted a large-scale study comparing DNA variations of more than 240 thousand people from around the world and found more than 500 genes that are associated with intelligence.