The contribution of colour to three-dimensional ambiguities in paintings and drawings.

This paper is about kinds of visual ambiguity that concern the author as a painter. Some effects of incompatible depth cues on the experience of looking at paintings and drawings are discussed. Particular attention is given to the role of colour as a depth cue. It is suggested that areas of identical pigmentation on different parts of a picture surface tend to be interpreted as being on the same plane. Where this interpretation is incompatible with other depth cues 'visual tension' results, the degree of tension being dependent on the relative strength of the cues involved. This hypothesis is illustrated and elaborated with the help of a number of line drawings.