Optical illusions are often said to fool the eye, but it is the brain, which interprets the information that our eyes take in, that is really fooled. Our brains are working hard all the time to make sense of the world we see. They have so much information to process, coming in from all our senses that they take short cuts, working on patterns they have met before. Sometimes those patterns do not make sense of a new situation.
We’re often told that seeing believes, but when it comes to matters of vision, our eyes have a habit of deceiving us. For centuries, people have been fascinated with optical illusions and eye trick, and with good reason: While they’re fun to look at — often challenging us to see things in new ways — they also reveal a great deal about how the brain interprets what we see and shapes our perception of reality. This April fool’s Day, we’re exploring the science behind these tricks that our own minds play on us.
Research on optical illusions highlights one major point: that our visual system is too limited to accurately process all of the information that our eyes take in, so it works on the basis of the most likely interpretation. On rare occasions, the brain interprets wrongly, causing us to perceive something inaccurately — an optical illusion. On other occasions, different people can perceive things in different ways. In fact, if you’ve ever struggled to see a “hidden” image in a single-image stereogram, or argued with a friend over the color of a dress you may have noticed that not everyone experiences visual illusions in the same way.
From straight lines appearing crooked to still images moving on the screen, here are some of the most well-known optical illusions, along with scientific explanations of why they occur.
The Herman Grid illusion was first reported by German physiologist Ludimar Hermann in 1870. As you look at the image, you’ll notice that dark dots quickly appear and disappear at the intersections between the grids. However, when you look directly at an intersection, the dot seems to vanish.
The explanation behind this illusion has been the subject of debate for years, with many claiming it’s the result of “lateral inhibition“— the complex way the cells at the back of the retina respond to black and white.
