Corners of our Eyes

The Science of It

The rods & cones in our eyes are not distributed evenly. They are much denser at the center and therefore our vision is clear only at this center. Everywhere else, it's foggy and undefined. Why don't we notice this? Because whenever we shift our eyes to look at a spot that was previously foggy...that spot becomes the center and we can see it clearly. Try focusing on one word in this paragraph and without moving your eyes see how many other words you can read. Not very many.

What does this mean? Well, it means we don't see 90% of what we think we see. We are constantly evaluating everything that's not right in the center of our eyeballs. We are especially sensitive to movement in our peripheral. (With good reason - how often do stalking predators walk right into our gaze?)

It also means that we could consider peripheral vision almost a sixth sense. Try this: Stare straight ahead. Raise your hand up so it's level with the side of your head. Wiggle your finger. Slowly move your hand around to your face. Do you notice how you can tell when it's within your line of vision...but you can't say anything else about it other than: it's there?

Close one eye, then the other The eye closest to your wiggling finger does see it, while the other eye doesn't at all and since your vision is a composite of both eyes, you (vaguely) see it and (vaguely) don't see it at the same time. Schrodinger's finger, if you will.

Practical Applications?
The first and most obvious use (to me, anyway) is to use whitespace to calm the eye. Most applicable to graphic design but useful elsewhere as well. If you want somebody to concentrate on something...empty all the space around it. The empty space will attract their vision anyway. (Perhaps this is why "trapped white space" is so bad...enough white space to surround something but not enough to clear our peripheral.)

Seeing movies on large screens is also an exercise in peripheral vision. Your eyes move around the screen like they would around a landscape, settling on details here and there. This allows us to "actively watch" a movie.

Peripheral vision also allows directors to fool us. Take a look at this shot from Jaws with some simple Photoshopping to approximate what it looks like to a first time viewer, focusing on Brody's eye or mouth.
Notice how the top row of shark teeth intersects Brody's eye and the bottom intersects his mouth? If our ancestors weren't hardwired to freak out atthat image, we wouldn't be here.

Horror movies are filled with this sort of stuff. I can think of several others off the top of my head. (The shark crashing into Hooper in the cage in Jaws, the Alien swooping down behind Brett in Alien, the alien grabbing Dietrich and so on, and so on)

Yeah, it can startle us, but lets think less about the techniques that have been used for it and what we can do in the future with it.