Eye-tracking for Neuroscience

What is eye-tracking?

“Eye-tracking” is a term used to describe the study of eye movements. You usually use this method when you want to track the gaze of the eyes (i.e. where someone is looking), when you want to measure the motion of the eye relative to the head, or when you want to study changes of the pupil (the black dot in the center of your eye) over time.

Why is eye-tracking useful for Neuroscience?

Did you know that eyes are a small part of your brain, which has pushed its way out of your skull in order to collect information about the world around you?

In vertebrate animals, or animals with a spinal cord, our nervous system starts out as a tube of neural tissue in the fetus. The part of this tube that is closer to the tail becomes the spinal cord, and the part of the tube that is closer to the head grows into the brain. The very tip of the neural tube on the brain side later grows into the cortex, the part that we are used to seeing as the “outside” of the brain. The cortex is actually the “front” of the brain, which has grown so big that it folded back over the rest of the brain. The very tip of the cortex, now folded back over the rest of the brain, then grows two long tendrils along the bottom of the brain, where they cross before forming eyeballs in the eye sockets of our skulls.

This means that your eyes are literally bits of your brain pushed out of your head into the world. When you look someone in the eyes, you’re actually looking at their brain!

So in a way, studying someone’s eyes is almost like directly observing their brain without cutting their skull open. Granted, the eyes are a very specialized section of the brain, so they can’t tell us everything about the nervous system they serve. But because eyes are a huge source of information for most humans, watching what someone looks at, for how long, can tell you a lot about what they find interesting or surprising, which in turn can help you guess their past experience and current feelings.