#12 Your Mood Controls Pupil Dilation
Any sort of excitement or positive thought can protract your pupils. When you’re feeling good about something or you get tempted towards anything, then your pupil expands up to 45%.
The same theory applies when you get petrified in any situation. When you get scared or nervous, the pupils tend to contract. So, the next time you break into a brawl with someone, notice their eyes to size them up.