The "false phi" illusion seems to be closely related to the "reverse phi" phenomenon, discovered by Stuart Anstis in 1970. In reverse phi, an object simulatenously moves and reverses contrast—and seems to jump the other way. Using the buttons above, "reverse phi" can be compared with "false phi". In reverse phi, the texture turns by 1° and reverses contrast on the same frame; in false phi (with brief adapter), the texture turns by 1° and reverses contrast on the next frame.

There's a great deal of variation in the amplitude of the two illusions from one observer to the next, but we have shown that they are closely correlated across observers.