Rotating face mask

from Michael’s Visual Phenomena & Optical Illusions


What to see

These are rotating face masks, the left filmed from an actual object, the right calculated with appropriate lighting conditions. Note that the ‘hollow’ (negative) version of both faces immediately switches back into a positive view, one cannot ‘hold’ it.


Positive and negative versions of the mask only differ in the position of the assumed light source, and a face is such a strong percept that it overcomes the “history” which is the only cue that the face is negative. On repeated requests, here is my attempt at a more detailed explanation:

Roger Garrett pointed out: If you concentrate on the rod that supports the mask in the right movie, you may be able to ‘hold’ the inverted view, at least a bit longer.

This phenomenon is related to “reverspective” and the cute little dragon from Binary Arts, based on a Jerry Andrus design to celebrate Gathering for Gardner 3 (16–18 Jan 1998 in Atlanta, Georgia).

A commentator (thanks!) recently made me aware of this sculpture. Can only be appreciated if you stand in front of it and move sideways, of course – no photo can bring out the phenomenon.


Top left movie: Adapted from Richard L Gregory✝ with his kind permission. Also seen at Your amazing brain with Richard’s commentary.

Top right movie: From the Max-Planck-Institut für biologische Kybernetik in Tübingen, with kind permission by H Bülthoff [BTW: The left face depicts a well-known vision researcher (KRG)]. <Link to the original movie>

Yellott JI & Kaiwi JL (1979) Depth inversion despite stereopsis: The appearance of random-dot stereograms on surfaces seen in reverse perspective. Perception 8:135–142

Hill H & Johnston A (2007) The hollow-face illusion: Object-specific knowledge, general assumptions or properties of the stimulus? Perception 36:199–223