Optical illusions that make you 'know but still get fooled'

They say "seeing is believing", but do you really believe what you see?

Looking at the image below, do you see the two orange circles are the same size?

Orange circle illusion. (Photo: Visme).

If the answer is yes, you have officially been fooled by an optical illusion. Even though we know the answer, we still have the impression that the orange circle on the left is smaller than the one on the right. However, in reality, they are the same size.

It's a classic 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 to see. Our brains have evolved to identify patterns, to make connections by interacting with the real world. It's a survival instinct.

However, when a visual situation arises that differs from what our brains perceive as the 'norm,' an optical illusion occurs .

It is the result of the brain's response to unusual visual experiences, and coming up with interpretations that seem "inappropriate."

Troxler effect. (Photo: Visme).

Stare at the center of the blurred image above without blinking. After a few seconds, do you see the image begin to disappear?

This optical 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, specifically ceasing to respond to stimuli that do not change over time.

In this case, you can see very clearly that the blurry image in the background has gradually disappeared from our consciousness.

Checker Shadow Illusion. (Photo: Visme).

In the famous optical illusion called the "Checkered Shadow Illusion" , the square marked with the letter A looks much darker than the letter B, right?

But in reality, they are the same shade of gray.

It's a classic example of how our visual system cannot perceive absolutely.

Here, the visual interpretation situation on the board is complex: There is light shining on the surface, then there is the shadow created by the cylinder, shining on both the light and dark squares .

This confuses our brains when determining the colors of squares A and B, resulting in incorrect judgments.

Purple flower illusion. (Photo: Visme).

After looking at the cross in the middle for a few seconds, you will start to see a green dot moving around. Looking longer, we will see the purple dots disappear.

An effect called "negative retinal afterimage" occurs when our perceptual 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 lilac dots gives rise to the appearance of afterimages of a complementary color (green).

Poggendorff illusion. (Photo: Visme).

Looking at the image on the left, the black line appears to be aligned with the blue line. However, in reality, the black line is aligned with the red line, as shown in the image on the right.

Johann Poggendorff, a German physicist, was the first to describe this illusion in 1860. It reveals how our brains perceive depth and geometric shapes, but the cause of this optical illusion remains unexplained.

Shepard's Illusion. (Photo: Visme).

Looking at the two tables above, you would believe that they cannot be the same size. At least the table on the left looks less square than the table on the right. However, in reality, the two table tops are exactly the same.

This simple yet amazing optical 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 experiences with the outside world and thus sometimes interferes with reality.

Specifically in this illusion, the perceptual error is due to our brains being unable to help but interpret 2D images as 3D and perceive very different dimensions due to foreshortened perspective.