The eyes have been called a window to the soul for centuries. A study from Brown University offers something narrower and more testable: a window into the precise moment the brain decides its current assumptions no longer apply.
The research, published in Nature Human Behavior and announced by the university on August 5, found that when people encountered information that violated their expectations, their pupils dilated and specific brainwave signatures increased. Those signals were not incidental. They tracked how much a person set aside prior expectations and how quickly they updated their predictions afterward.
