The eye may not be the window to the soul in the conventional sense, but it is a window into the intricate workings of the mind.

The pupil of the eye fluctuates and varies a lot in humans and many mammals. If tracked during the day, the pupil will not only respond to changes in external stimuli such as light, but also to internal conditions such as attention and emotional states. It is a signifier of what goes on in a person’s head and is linked to brain activity. Does this revelatory beh