Optical illusions are one thing, but there are also images that can rewire your brain for a very long time. It’s a scary thing, and Tom Scott explains.
The McCollough effect is a strange phenomenon in which gratings in one color appear a different color depending on the orientation of the gratings. For example, if someone alternately stares at a red horizontal grating and a green vertical grating for long enough (15 sec to 5 min), a black-and-white horizontal grating will then look greenish or a green colored object may actually look red. This phenomenon apparently doesn’t work on a retinal level but rather a cognitive one, and can affect a person for up to three months.