Normally, a person's pupils naturally widen (or dilate) in low-light environments to allow more light into the eye. However, in a new study, researchers reported that a person's pupils also dilate when they are concentrating on tasks. In particular, they found that the more a person's eyes dilated during the task, the better they did on tests measuring their working memory.
Read more …Eye-opener: Pupils enlarge when people focus on tasks