Pupil dilation typically occurs when we process new information or respond to changing environments. But in a recent University of California, Berkeley study, researchers have found that weaker pupil response is associated with high anxiety. Study leader Sonia Bishop says that this suggests why highly anxious individuals may find it harder to make decisions in volatile environments.

"In low anxious individuals, their pupils really track information in volatile or changeable situation. And so it’s suggesting that there’s this implicit processing of that information which is working well. But in high anxious individuals, we don’t see that tracking, so their pupils are not responsive to their information. So this suggests there’s something wrong in that system of the brain which deals with sending out that signal that this is important information."

Bishop says that the findings may lead to better therapies and targeted drugs for anxiety.

"So one suggestion could be that that system is kind of misfiring and if we give people drugs based on that system, we might be able to normalize it."