Pupillometry - The Eyes Have It

Since I spend a lot more time in the dark looking at holiday displays in December than other months, it got me thinking about the way our pupils open and close.

This is called pupillometry and it isn't just limited to adjustments to light. Pupils also dilate when a person is anxious, excited, and working on math problems! 

In fact, the pupil serves as a sensitive indicator of cognitive, emotional, and sensory responses in psychological research. The eyes really do serve as windows to the soul or at least the brain. For more details on pupillometry, check it out.