What is Artificial Intelligence?

The two orange circles are exactly the same size; however, the one on the left seems smaller.

Optical or visual illusions have various effects of perception on the brain. A Scottish psychologist, Marty Doherty, suggests "that the brain’s capacity to consider the context of visual scenes, and not just focus on parts of scenes, develops slowly" that's why most kids have largely different perception over a visual illusion context.

In this particular study, Marty Doherty applied the famous Ebbinghaus illusion (sometimes called the "Titchener illusion"). Named for its discoverer, German psychologist Hermann Ebbinghaus (1850-1909) Ebbinghaus illusion consists of a circle surrounded in one image by smaller circles, and in another by larger circles. The viewer tends to perceive the circle surrounded by smaller circles as being larger than the circle in the other image, even though both are exactly the same size. The difference in size perception is due to the surrounding visual cues (larger or smaller surrounding circles), and the way the brain processes these visual cues.

Using the Ebbinghaus illusion, Doherty conducted various tests to 151 children, ages 4 to 10, recruited from a Scottish primary school and nursery school. Another 24 volunteers, ages 18 to 25, were college students. The participants were all provided with 1) Control Images, 2) Misleading Images and 3) Helpful Images.

Control images showed only two orange circles. Click here to see the image.

Misleading images showed the smaller orange circle surrounded by even smaller gray circles to boost its apparent size. Large gray circles surrounding the larger orange circle were intended to shrink its apparent size.

In helpful images, large gray circles surrounded the smaller orange circle to make it appear smaller than it actually was. Small circles surrounded the larger orange circle to magnify its apparent size.

Test results showed that for 4- to 6-year-olds, accuracy of size perception for misleading images remained at about what it was for control images. Misleading images increasingly elicited errors from older children and tricked adults most of the time. Adults made almost no errors on helpful images. Kids from age 7 to 10 erred on a minority of helpful images, while 4- to 6-year-olds performed no better than chance.