What causes our eyes to widen when afraid?

Question

Is there some kind of evolutionary reason for this?

Answer 1

maybe its some kind of response to fright because the farther your eyes are open, the more you can see with your peripherals, thus seeing my potential threats. thats just my guess

Answer 2

Fight or flight response..."fight" or "flee" from perceived attack, harm or threat to our survival.  Yes it is evolutionary.

Answer 3

I would say that when you are afraid, you think that something is near you-sometimes-other scenarios can go along with this too---and you open your eyes to get a better view of whats around you b/c u r too scared to move.

And when you are surprised, you open your eyes to get a bigger view of whats going on around you.

Its just reflexes and reaction.

Answer 4

adrenaline....

Answer 5

maybe because it let's in more light

or some instinctive way to see more

or even to do the small animal thing

where we make ourselves seem bigger

Answer 6

Sympathetic nervous system, which is part of the autonomic nervous system, simple overview:

http://faculty.washington.edu/chudler/au...

It is "unlearned",  "autonomic"....readies animals to run or fight to survive.  (college psych prof)