Eye-Tracking Studies

What do they tell us about reality?

This heat map based on eye-tracking technology, shows an average of where people’s gaze rested on this image. The uncolored parts of the image were not really seen at all — just filled in with good-enough approximations. The background is almost not seen at all.

MOST of what we humans call the World is constructed by vision. Our brains are wired for processing light and space. Cognitive scientists say that every major brain area receives visual information. In a sense, we think with our visual circuits, if zoologist Andrew Parker is correct. In his book, In The Blink Of An Eye: How Vision Sparked The Big Bang Of Evolution, Parker theorizes that evolution has been driven by sight since the appearance of eyes in the fossil record 550 million years ago.

Yet, we don’t pay much attention to that World. Eye-movement research has shown that we make lots of brief, high-definition fixations, each about the size of a thumbnail, as we scan and sample areas of interest in our environment: hands, faces, pectoral muscles, another car, etc. But, in between fixations, during the saccades that are completely unconscious and blindingly fast, 70–100 times per second, — we are blind. To save brain space and processing time, this vast space between focal points is filled in from memory or best guesses, like a quick puzzle made of bits and pieces of low-resolution imagery.

After reading Eye Tracking and Web Usability: A Good Fit?: A look at the science and value behind eye tracking usability studies, by Nicholas Gould and Jesse Zolna, I became so excited that I lay awake that night, thinking about the sort of a dream world we live in. Things that seem solid are mostly empty space, like the Buddhist sages have always said.

We think of the world as continuous, complete, and mostly permanent. It appears high-definition, but very little is based on actual data. It’s mostly a sampling of points we think are important with the in-between areas filled in to create the illusion of a seamless, permanent world. Much of what is right in front of us, we don’t really see, even when it’s staring us in the face.

Eye-tracking technology has helped us understand how heavily edited our view is behind the scenes. We experience our eyes as if they are video cameras, but the actual result is much more subjective. We live in something more like a photoshop collage. In fact, we each see a slightly different world, like a movie set that we walk around in, heavily influenced by our expectations and habits, saturated by the hormones of emotion, with an overlay of chatter and thinking—it’s more like a personal screenplay than concrete fact.

This is something to keep in mind when doing research with humans. We can use computers and eye-trackers to see precisely where each saccade rests for it’s brief moment. But as for what’s happening in the mind of the viewer , we still have to listen and use our best guess — we are still in the dark.

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