When you look at something, what you’re really seeing is light, specifically light from the sun or a light bulb, that bounces off whatever you’re looking at and enters your eye. The light is then converted to electrical signals that your brain can turn into an image. This process takes about one-tenth of a second; so at any given moment your eyes are taking in an incredible amount of information. Because it’s really difficult for the human mind to take in everything at once, our brains take shortcuts to simplify what we see so that we can concentrate on what’s important. While this trait helped early humans survive faster predators, these shortcuts are also at the heart of how optical illusions fool our brains.
Optical illusions are images or pictures that occur when our eyes send information to our brains that tricks us into perceiving something that does not match reality. We live in a three-dimensional world, and our brains gather three-dimensional cues about depth, shading, lighting, and position to help interpret what we see here. The mismatched cues between a three-dimensional world and a two-dimensional image can be fodder for the birth of Optical Illusion land, a realm where perception and reality can be very different things.
Optical illusions are based in science, and brilliant men and women have researched what opens the doorway to the brain being deceived by what the eyes take in. Curiosity and creativity have challenged these intellects to design some mystifying visual illusions that can entertain while teaching us how our amazing brains work.
The number and diversity of these illusions is mind-boggling. I started this quest as a way to illustrate that seeing is not always believing. I now feel as if I returned to graduate school to learn the particulars of a very complicated subject. I have to tell you though; it has been fun and enlightening. I’m going to give you a short list of illusions based on brain processes:
- The Mach Band illusion uses a stack of gray bars that seem to be lighter on the bottom but when separated are actually a solid color. This is due to an automatic process in our brain that is called lateral inhibition. This process helps us find the edges of an object.
- The Moving Snake illusion uses something called peripheral drift that can make a still image seem as if it’s moving. The illusion is caused by the brain’s interpretation of patterns seen outside of the eye’s area of focus. The Moving Snake illusion is an impressive example of this. You just can’t help but see an impression of the slithering, circling motion when you look at it. However, when you focus on any one point of this illusion, the motion seems to stop. This is due, in part, to how we perceive light and dark and, in part, to our eye movements. The sequence of light and dark color segments in each of the snakes fools the motion sensitive neurons in our brains into responding as they would to real physical motion.
- The Lilac Chaser is the result of something called the “negative retinal afterimage”. The changes become visible after about three seconds of constant view (we typically move our eyes three times per second; so this phenomenon presents no disadvantage to normal viewing). Negative retinal afterimage is normally a good thing because it helps color constancy – the ability to see colors somewhat independently of changing light.
- The Jesus Illusion is an example of an ambiguous or reversible figure. In other words, because these forms exploit graphical similarities and other properties of the visual system, a human observer can identify two or more distinctive image forms from a single picture.
The only thing actually bending and buckling is your mind. Perhaps now you might want to believe the old cliché “What you see isn’t what you get.”
Tilt your head to the right and look at the picture. Voila! The C’s in the two words become the cat’s eyes, and your brain does the rest. This is an example of an ambiguous or reversible figure.
The Ames Room
Both people are the same size. You assume they are standing in an ordinary room. However, that is not accurate, and great care has been taken to make sure that most of the information about the true shape of the room does not meet the observer’s eye. The room is trapezoidal not rectangular; the ceiling is lower on one end; all objects in the room contribute to the illusion.
Tilt your head to the left to see the man; tilt you head to the right to see the word Liar written in longhand. Hence, the question, “would you trust this man?”
You see a pinkish-violettish blob, one of which briefly disappears, circling around. Then, if you have been focused and staring, you will actually see a rotating green spot. When you shift your gaze, the pinkish circle reappears.
One view is a full-face drawing of Jesus with His long, flowing hair. The second view is of Jesus on a donkey with a crowd of people around Him. If you look at the right side of the drawing about mid-point, I think you will be able to focus on the details of the crowd scene.
Gestalt psychologists use the Kanizsa “triangle” to describe the law of closure which claims that objects grouped together are seen as a whole. We “see” three black circles and three black triangles. Technically, there are no circles or triangles in the picture.
MOVING SNAKES ILLUSION OR SPINNING CIRCLES ILLUSION
Could you see the snakes/circles spinning clockwise and counter clockwise. Boy! I could and can. There is no movement.
Yes, there is a secret. There is a man looking out at you from the rocks. It is a full face, front view, eyes toward you.
INVERTED OPTICAL ILLUSION
You see what appears to be a photograph of a dark-haired young woman in the white square rather than the negative image on the left side of the illusion.
Well, we’ve come to the end of this optical illusion journey. We’ve had some fun, but the underlying message is a very important one. Sometimes “seeing isn’t believing”. Sometimes “seeing is deceiving”. What does that mean for you and for me? What if you have judged yourself as not enough based on your sense of sight?