A team of researchers from the Georgia Institute of Technology investigated the relationship between pupil size and intelligence in 500 Atlanta volunteers, aged 18 to 35. They were asked to take tests on thinking, attention and memory. It turned out that dilated pupils show 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 initial pupil size between those who scored the highest and lowest scores on intelligence tests could be seen with the naked eye. And this may be due to the fact that people with large pupils have a better level of brain activity in the area associated with intelligence and memory. Scientists also noted a negative relationship between pupil size and age: older volunteers, as a rule, had smaller and more constricted pupils.
Pupil size is associated with an area known as the locus coeruleus, a blue spot in the upper brainstem that spreads to the rest of the brain via neural connections. It releases a chemical that functions as a hormone in the brain and body, and acts as a neurotransmitter for regular processes such as perception, attention and memory. This same area plays an important role in helping distant regions of the brain work together to perform complex tasks.
The scientists formulated the result 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.
Earlier, Scottish scientists found out the source of high intelligence in children. A group 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.
