Have you ever noticed that signposts and trees on the side of the road seem to whoosh by faster right as you drive past them, or that a door frame seems to curve outward as you approach it? These are just two examples of real-life movements that underlie more than 50 types of illusions, now systematically organized and explained by scientist Mark Changizi.
The systematization also lends a glimpse into how illusions are not simply tricks your brain likes to play on you; they are manifestations of how the visual system evolved to keep up with real-life motion.
| According to the research done by Assistant Professor of Cognitive Science at Rensselaer Polytechnic Institute Mark Changizi, it takes our brain nearly one-tenth of a second to translate the light that hits our retina into a visual perception of the world around us. While this neural delay may seem minuscule, imagine trying to catch a ball or wade through a store full of people while always perceiving the very recent (one-tenth of a second prior) past. So the problem is if a ball is passing within one meter of you and traveling at one meter per second in reality would be roughly six degrees displaced from where you perceive it, and even the slowest forward-moving person can travel at least ten centimeters in a tenth of a second. Changizi says simple actions like catching a football or moving through a room full of people requires more than just responding to the surrounding quickly. It requires our ability to foresee the future. He claims the human visual system has evolved to compensate for neural delays, allowing it to generate perceptions of what will occur one-tenth of a second into the future, so that when an observer actually perceives something, it is the present rather than what happened one-tenth of a second ago. Using his hypothesis, called “perceiving-the-present,” he was able to systematically organize and explain more than 50 types of visual illusions that occur because our brains are trying to perceive the near future. |
According to Changizi:
Illusions occur when our brains attempt to perceive the future, and those perceptions don’t match reality. There has been great success at discovering and documenting countless visual illusions. There has been considerably less success in organizing them.
My research focused on systematizing these known incidents of failed future seeing into a ‘periodic table’ of illusion classes that can predict a broad pattern of the illusions we might be subject to.
He further explains that we experience countless illusions in our lifetime. The most famous being geometrical illusions — those with converging lines and a vanishing point we often see in Psychology 101 classes or in entertaining optical illusion books.
For example think of the Hering illusion (shown below), which looks like a bike spoke with two vertical lines drawn on either side of the center vanishing point. Although the lines are straight, they seem to bow out away from the vanishing point. The optical illusion occurs because our brains are predicting the way the underlying scene would project in the next moment if we were moving in the direction of the vanishing point.
The Hering illusion - Image courtesy of Rensselaer Polytechnic Institute
He explains:
Evolution has seen to it that geometric drawings like this elicit in us premonitions of the near future. The converging lines toward a vanishing point are cues that trick our brains into thinking we are moving forward — as we would in the real world, where the door frame seems to bow out as we move through it — and we try to perceive what that world will look like in the next instant.
He is the lead author of this research published in May-June issue of the journal Cognitive Science. Coauthors on the paper include: Caltech Biology Professor Shinsuke Shimojo, former Caltech undergraduate student Andrew Hsieh, and former Caltech postdoctoral researcher Ryota Kanai, as well as Romi Nijhawan, a psychologist at the University of Sussex in England.
Changizi has identified 27 other classes of illusions organizing them into 28 predictable categories, classified on a matrix that distributes them among four columns based on the type of visual feature that is misperceived (size, speed, luminance, and distance) and among seven rows based on the different optical features that occur when an observer is moving forward.
0 responses so far
There are no comments yet...Kick things off by filling out the form below.
You must log in to post a comment.