I found this really interesting. I never thought about it before but I do realize that most, if not all, animals don't show the sclera in the eye which is likely why in movies like horror or scifi, if a person doesn't show the whites of their eyes it's so unnerving to see. Psychologically, this is actually a really interesting experiament and would be fun to expand on with another experiament.

Saliently- Meaning stand out more or more prominent

wasn't sure where exactly the muscle was located so I looked it up and here is a picture.