Multistable perception

Because most of these images lead to an alternation between two mutually exclusive perceptual states, they are sometimes also referred to as bistable perception.

They are spontaneous and stochastic events that cannot be eliminated by intentional efforts, although some control over the alternation process is learnable.

Multistable perception was a common feature in the artwork of the Dutch lithographer M. C. Escher, who was strongly influenced by mathematical physicists such as Roger Penrose.

For humans, the "default" interpretation comes from an assumption of top-left lighting, so that rotating the image by 180 degrees can cause the perception to suddenly switch.

[8] In literature, the science fiction novel, Dhalgren, by Samuel R. Delany, contains circular text, multistable perception, and multiple entry points.