For more than a century, scientists have known that our pupils respond to more than changes in light. They also betray mental and emotional commotion within. In fact, pupil dilation correlates with ...

Dilation and constriction of the pupils reflect not only changes in light intensity but also ongoing mental activity. The response is a measure of interest, emotion, thought processes and attitudes ...

The science of pupillometry takes a common intuition — that you can tell a lot about someone when you look them in the eye — and makes it concrete, measurable, and extraordinarily useful.

Pupil width declines by around 0.4 millimeters per decade "Our results confirm the hypothesis that the pupil's ability to adjust to varying light situations decreases as we get older.