Today’s factismal: Your retina actually processes images before they are sent to the brain; this is the cause of many optical illusions.
One of the more interesting things to do when you are stuck in a tiled waiting room is stare at the floor. If you are lucky, then the floor tiles will be arranged so that they look like little three-dimensional boxes; they will be an optical illusion. (And with a little training, you can make the boxes flip-flop.) But what drives that illusion? It turns out that optical illusions are great tools for examining how we see and how we think. They reveal our innate preconceptions and our social training, and can (and have!) keep a researcher busy for his entire life.
A researcher like Ewald Hering, who was born 180 years ago today. Ewald was fascinated by how we perceive things, and invented one of the earliest and best-known optical illusions. Known today as the Hering illusion, his little trick helped show that the retina actually interprets part of the image it sees before sending it on to the brain. Though this may seem surprising, it helps to remember that the retina is actually a very specialized bit of neural tissue that some have called “the only visible part of the brain”. For example, some psychologists say that the retina interprets the radial lines in the Hering illusion as being similar to what parallel lines meeting at infinity; if that is the case, then the two vertical lines must be curved. Of course, they aren’t – but our retinas don’t know that! Because they impose an innate pattern they change a pair of straight lines into curved ones.
What is more fascinating is that this sort of misperception happens with all of our senses. We can have audible illusions, tactile illusions, taste illusions, and even prioceptive illusions. We can also have illusions about how we peceive the social world. And that’s what the folks at Project Implicit are testing. They want to find out how our preconceived notions interfere (or don’t) with our abilities to view each other as people. If you’d like to help, then why not head over to the website?