Optical Illusions and Visual Illusions

For centuries, curious people and doctors have investigated optical illusions as a way to understand how the human brain works. Optical illusions are essentially characterized by an altered perception of an external stimulus, slightly or greatly different from the real physical event.

Optical illusions can be divided in two great families: the first, that we will call physiological illusions, are caused by a stimuli overload, or excessive stimulation of our visual receptors, resulting in a slightly altered perception of color, shape, depth or motion. The second family, which contains the so-called inference illusions is rather caused by "inferences" in our brain: we have inherited some neural patterns that let our brain respond automatically to visual stimuli in some kind of "neural reflex". It's really the same thing when we think about the patellar reflex (when you hit the rotula's tendon in your knee, your quadriceps contracts), except this time the reflex is in our brain, which "guesses" what is going to happen next and sends us a modified version of what it really received as a signal.

On this site, visual and optical illusions are divided by the effects they create (e.g. color glitches, shape distortion) along with the most famous scientific and "underground" experiments and figures.

We also feature a section about the left and right brain conflicts, which contains very curious animations and images that are perceived differently by different people, depending on whether that person has a dominant right or left hemisphere.

When possible, we've tried to provide animated versions for moving illusions, you will often find at least one, possibly more, media associated with a specific visual illusion or experiment.

Enjoy the illusions and please consider sharing them with your friends and family, some of them are really puzzling and will entertain people of all ages, from children to adults, from the masses to the specialized neurologists.