The Number Optical Illusion: A Test of Contrast Sensitivity A viral optical illusion has sparked debate on Twitter as people disagree on which number is hidden within a black and white circle. The ...

Can you find 2 hidden cats in this mind-bending optical illusion in just 5 seconds? Test your IQ, observation skills, and ...

In today's optical illusion challenge, a tricky brain teaser tests your observation skills. Hidden among a sea of "20s" is a ...

The peripheral drift illusion causes us to perceive motion in a still image. A new study shows that the mechanism of this illusion relies on changes in pupil size.

Optical illusions are not merely a trick of the eye—they play tricks on how effectively your brain handles visual information. These puzzles play with contrast, depth, and symmetry, confusing ...

The contrast of figures C and D is exactly the same as well, but they are perceived differently. The perception of this illusion was weaker among the depressed patients than the control subjects.