Ambiguities in 3-D patterns induced by lighting assumptions

Papathomas T.V. & Gorea A. (1990). Perception, 19, 569-571.




A bistable pattern presented under its four 90 rotations. The white and black, horizontal and vertical bars produce an impression of slabs stacked up in depth either away (a) or toward (b) the observer. It is postulated that these precepts are induced by the observer's assumption on the location of the light source. When rotated as in (c) and in (d), the arrangements of the white and black bars in the top and bottom parts of each panel obey opposite lighting assumptions hence inducing opposite/conflicting bistable precepts in each half.




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