When light hits our retina, it takes about one-tenth of a second for our brain to translate that signal into perception. Evolutionary neurobiologist Mark Changizi says this neural delay makes our brains generate images of what it thinks the world will look like in one-tenth of a second. It's not always right.
“Your brain is slow, so you need to basically create perceptions that correct for that delay,” said Changizi, director of human cognition at 2AI Labs.
Creating an image of the very near future probably kept early humans alive because it kept them from bumping into dangerous objects or being attacked by a fast-moving predator.
Click through the following images and see how our ability to predict the future one-tenth of second in advance also messes with your mind.
When images of objects flow across the retina, it activates all these different neurons in our brains. This is the mechanism by which the brain figures out how to extrapolate the next moment.
“When you move through the world, your eyes take snapshots,” said Chingazi. “During that snapshot, as something moves across your visual field, you don’t just end up with a dot on your retina, you end up with a blurred line on your retina.”
Our perception doesn’t see them, but the blurred lines make our brains realize that something is in motion. From there we can determine the direction of an object moving in our world. Since the blurred lines are all emanating from a single point in your visual field, they can inform you on the direction you’re going.
“Once you know the direction you’re going, you can determine how all these things would change in the next moment,” said Chingazi.
Take the above photo of “warp speed.” You don’t even have to question in what direction those blurred lines are taking you. Little did you know, "Blurred Lines" is more than just the most over-hyped song of the summer.
Perhaps the best representation of blurred lines and how they apply to optical illusions is the Hering illusion. Its radial spokes are blurred lines, all emanating from a single point. Those lines tell us where we are heading: forwards, towards the center.
The reason the two vertical lines appear to bow in the middle is because the radial lines suck our field of vision towards the center, as if we were in motion. In fact, those vertical lines are parallel, despite what our brain tells us. Our perception is actually showing us what those parallel lines look like in the next tenth of a second, the moment our gaze “passes through” the vertical lines, towards the vanishing point of the radial lines.
To simplify things, Chingazi suggests we imagine walking through a very tall doorway of a cathedral. When we’re really far away, the doorway sides seem parallel to one another. The angular distance between the top, middle and bottom of the door are all roughly the same.
“Once you’re really close or going through the cathedral doorway, the parts at eye-level are going to be wider apart,” he said. “When you look up, they actually converge like railroad tracks in the sky.”
Essentially, this is the same phenomenon that happens in the Hering illusion.
Shapes aren’t the only objects that change as we move forward. Other factors like angular size -- how much of our visual field is taken up by an object – speed, distance and the color contrast between an object and its background also contribute to optical illusions.
Changizi determined that many illusions can be defined within his future-seeing process, so he created a chart with 28 categories that help organize what he calls his “grand unified theory.”
“This seven-by-four table really has one hypothesis that explains them all,” he said. “It makes a prediction across these 28 categories about what kind of illusions you should expect and how the illusions will reveal themselves across these 28 kinds of stimuli.”
The above illusion was created by a former student of Chingizi’s, and it demonstrates elements of speed, size and contrast. Move your head towards the center and the bright-white center appears to quickly fill the circle. Move your head backward and the dark perimeter appears to close in on the white center.
The orange circle on the left appears much smaller than the one on the right, when in fact they are the same size. This is the classic Ebbinghaus illusion, named after Hermann Ebbinghaus, the German psychologist who discovered it. British psychologist Edward Titchener popularized the illusion in the early 20th Century, as the illusion is also known as “Titchener circles.”
The juxtaposition of the circles’ sizes and distance from each other make them appear incongruent.
Read more at Discovery News
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