Wondering why Optical Illusions Work?

Did you ever wonder how optical illusions work? 

If yes if the answer, you are going to enjoy reading this article a lot. Here is the explanation:

1.We have to understand how our brains process information. Our brain is neither linear nor logical in processing information. And as we will see later, this plays a big role in optical illusions.

2.Our brain fills in the gap while processing information.

3.Our visual system has evolved to predict things one-tenth of a second into the future. When light hits our retina in the eye, about one-tenth of a second goes by before the brain translates that into a visual perception of the world. Our brains have evolved to compensate for this neural delay. And it attempts to generate an image of what it will perceive one-tenth of a second in the future.

This is a very very important point. Optical illusions occur when what our brains predict does not match the reality.

Here are a few examples:


In which direction does the lady above rotate? Clockwise? Or anti-clockwise?

Can you close your eyes and re-open to see if the lady changes direction?


Focus on the middle and the left lady first. Now focus on the middle and the right lady. Were you able to change directions now?

The original direction of rotation that our brain perceives in the first half a second will persist. Until you close your eyes. Or take help of colours, whose rotational direction can’t be faked.

—You wno’t bvleiee the tihngs you wlil cmoe acosrs in the nxet 20 mnitues —

Can you read the above slide? Why?

It dseno’t mttaer in waht oderr the lterets in a wrod are, the olny irpoamtnt tihng is taht the frsit and lsat ltteer be in the rhgit pclae.—

Think about a tool and a colour!










Did you think of a red hammer?

About 75-80% of the people think of a red hammer when asked the question.

Over 95% of the people at least think of a hammer. While the colours may change. The second best option that people think of is a blue hammer. And the third best is a black hammer.

This is the reason to keep in mind: associative memory. We are all wired to pull out certain things from our memory when dealt with specific stimuli.

“The human visual system has evolved to compensate for neural delays by generating images of what will occur 
one-tenth of a second into the future.” – Mark Changizi

In summary: optical illusions occur when what our brains predict don’t match the reality. And this prediction-reality mis-match occurs due to:

•  how our brain processes information and

•  how our brain calls on our associative memory

Here is the link to the detailed explanation.