Pupil Facts

When you look at someone you love, your pupils dilate. Surprisingly, they also dilate when you look at someone you hate — both emotions trigger the same arousal response.

The pupil of the eye expands as much as 45 percent when a person looks at something pleasing.

Sheep, goats, octopuses, and toads have horizontal, rectangular-shaped pupils that give them a nearly 360-degree field of vision.