The Ebbinghaus illusion 2/52


52 weeks 52 different Optical Illusions

I love optical illusions so i thought i would share a few of my favorite and with many people opting to take up 365 day challenges i thought i would try a 52 week challenge in which i will share with you a different Illusion every week. so if you have any you would like me to feature get in touch.

Week 2

The Ebbinghaus Illusion 2/52

Observe the two sets of circles below. Which of the orange circles is larger?


You may be surprised to find out that they are exactly the same size. The deception occurs because of the size of the surrounding blue circles and their relative distance from the central orange circle.

These adjustments cause the brain's visual perception system to distort the relative size of the inner circles. Another factor at play is the "completeness" of the surrounding circles; if we removed a few of the blue dots or spaced them out, the illusion would not persist.

The two orange circles appear to be different sizes, but they are the same. The one on the left appears larger because of its context within the grey outlined circle. The Ebbinghaus illusion was discovered by the German psychologist Hermann Ebbinghaus (1850–1909).The illusion was popularized by Edward B. Titchener in a 1901 textbook, in English, which is why the illusion is sometimes called "Titchener circles".

The Ebbinghaus illusion is one of several size contrast illusions to have been studied by both philosophers and cognitive scientists. Bela Julesz (1928-2003), a Hungarian neuroscientist and experimental psychologist hypothesised that the illusory effect of the Ebbinghaus discs cannot be explained entirely in terms of retinal processes (Julesz 1971).

The illusion is similar to a Delboeuf Illusion, shown below. 


The two black circles appear to be different sizes, but they are the same. The one on the left appears larger because of its context within the white outlined circle. 

Interestingly, these illusions are perceived differently by adults and children, which provides evidence that they are context-sensitive. Because adults have higher sensitivity to context, illusions of this type fool them more often and more easily. Since children are not as context-sensitive, they are less often deceived by this kind of illusion.

What are the best optical illusions you've found on the web? Do you have more amazing examples you don't see here?

Share your thoughts with us in the comments section below.