People say “you believe what you see”, but do you really believe what you see?
Look at the image below, do you see 2 orange circles of the same size?
Orange circle illusion. (Photo: Visme).
If the answer is yes, you’ve officially been fooled by an optical illusion. Even though we already know the answer, we still have the feeling that the orange circle on the left is smaller than on the right. However, in reality, they are the same size.
It’s a good example of how optical illusions work. They can be seen as a form of challenging our perception of reality.
Science says we see by learning how to see. Our brains have evolved to identify patterns, make connections by interacting with the real world. It is a survival instinct.
However, when a visual situation arises that is different from what our brains call the “norm,” an optical illusion occurs .
It is the result of the brain’s response to unusual visual experiences, and arriving at interpretations that seem “inappropriate”.
The Troxler effect. (Photo: Visme).
Stare at the center of the blurred image above without blinking. After a few seconds, do you see the image start to disappear?
This visual illusion is known as the Troxler Effect , first discovered by Swiss physician Ignaz Paul Vital Troxler in 1804.
It reveals how our visual system adapts to sensory stimuli, namely by stopping responding to stimuli that do not change over time.
In this case, you can very clearly see that the blurred image in the background has gradually disappeared from our consciousness.
Checker Shadow Illusion. (Photo: Visme).
In the famous visual illusion called the “Checkered Shadow Illusion” , the square marked with the letter A looks much darker than the letter B, doesn’t it?
But in fact, they have the same gray color.
It’s a classic example of how our visual system is absolutely not perceptive.
Here, the situation of visual interpretation on a chessboard is complicated: There is light shining on the surface, then there is a shadow created by the cylinder, which shines on both the light and dark squares .
This confuses our brain when determining the colors of squares A and B, resulting in incorrect judgments.
Eggplant illusion. (Photo: Visme).
After looking at the cross in the middle for a few seconds, you’ll start to see a green dot running around. Looking longer, we will see the purple dots disappear.
An effect called “negative retinal afterimage” occurs when our cognitive system adapts to fill in the gap left by the “afterimage” of complementary colors on a neutral color.
In this case, the disappearance of the mauve dots creates the appearance of afterimages of additional color (green).
The Poggendorff Illusion. (Photo: Visme).
Looking at the picture on the left, the black line seems to align with the blue line. However, in reality, the black line is aligned with the red line, as shown in the image to the right.
Johann Poggendorff, a German physicist, was the first to describe this illusion in 1860. It reveals how our brain perceives depth and geometric shapes, but the cause of optical illusions. This has not yet been satisfactorily explained.
The Shepard Illusion. (Photo: Visme).
When you look at the two tables above, you will believe that they cannot be the same size. At least the table on the left looks less square than the one on the right. However, in reality, these two countertops are exactly the same.
This simple yet amazing visual illusion was presented by American psychologist Roger Shepard in his book Mind Sights (published in 1990).
It shows that our visual system is largely influenced by our experience with the outside world and thus sometimes interferes with reality.
Specifically in this illusion, the perceptual error is caused by our brain’s inability to 3D interpret the 2D images and perceive very different dimensions due to the shortened perspective.