What is an Optical Illusion?

Optical Illusions can use color, light and patterns to create images that can be deceptive or misleading to our brains. The information gathered by the eye is processed by the brain, creating a perception that in reality, does not match the true image. Perception refers to the interpretation of what we take in through our eyes. Optical illusions occur because our brain is trying to interpret what we see and make sense of the world around us. Optical illusions simply trick our brains into seeing things which may or may not be real.

Try out some of these illusions and discover just how tricky it can be for your brain to accurately interpret the images from your eyes. Click on any of the images below to begin your exploration of optical illusions.


Are the pinwheels moving?

Answer: No, the wheels are not turning. The Moiré effect can produce interesting and beautiful geometric patterns.

Light Bulb

Stare closely at this light bulb for 25 seconds. Then immediately stare at a white wall or sheet of paper. What do you see?

Answer: You should see a glowing light bulb!

Elephant Legs

How many legs do I have?

Answer: Four


In this illusion you can see the word Teach and its reflection. Can you read the reflection too? What does it say?

Answer: Learn

The Animal

How many animals do you see in the image?

Answer: Look closely, you should be able to see a rabbit and a duck.

The Box and the Sphere

Keep your eyes on the dot. Is it in the front or in the back of the cube?

Ask a friend and see if they agree!

Color Blind

What number do you see in the circle?

Answer: You should be able to see the number 26, but people with various degrees of color blindess may only see the 2 or the 6. 

Color Illusion

How many colors are present in the image?

Answer: One shade of green and one shade of red!&nbsp;<br /> <br /> It may look as if the two arms of the &quot;X&quot; use different shades of red, but in face the whole &quot;X&quot; only uses a single shade of red. Likewise, only one shade of green is present throughout the image.&nbsp;


Which side of inset bar is darker?

Answer: They are both the same shade!

Hermann Grid Illusion

Count all the black dots you can see

Answer: There are no black dots.<br /> <br /> If you focus directly on each dot, you&#39;ll see that all of them are white.&nbsp;

Horizontal Lines

Are the horizontal lines sloping or straight?

Answer: All of the lines are straight.<br /> <br /> The black and white blocks are not aligned and thus fool your brain into thinking that the lines are sloping.

Kanizsa Triangle

How many triangles are present in the image?

Answer: There are no triangles.<br /> <br /> In reality there are only 3 V shapes and 3 shapes that look like Pac-Men.

Muller-Lyer Illusion

Take a very close look at the 2 vertical lines. Do you think one line is longer than the other?

Answer: They are the same size! Hard to believe; get out your ruler to measure the lines and see for yourself!

My Wife and My Mother-in-Law

How many figures can you see in the image below?

Answer: If you look closely, you can see both a young and an elderly woman.<br /> <br /> The picture, My Wife and My Mother-in-Law, is a good example of two images existing in one, and was published in 1915 by the cartoonist W.E. Hill.


Are the circles moving in the image?

Answer: Look closely, they aren&#39;t moving.

Zollner Illusion

Do you think these lines are parallel?

Answer: They are parallel!

Refraction Illusion

Are both arrows pointing the same direction on the paper behind the glass?

Yes! This illusion demonstrations <a href="~/what-is-optics/refraction/">refraction</a>, the bending of light.&nbsp;