Perception of pictorial depth cues by pigeons

Pigeons were trained to discriminate pictures of intact objects from pictur es of objects in which both depth from shading and depth from perspective c ues were manipulated. Depth from shading was manipulated either by scrambli ng or by removing three-dimensional shading cues. Depth from perspective wa s manipulated either by presenting pictures df objects with a two-dimension al outline (i.e.., a square) or with a three-dimensional outline (i.e., a c ube). Transfer tests with novel images suggest that pigeons perceive and ut ilize both types of pictorial depth cues. The implications of these results for our understanding of picture perception in pigeons are discussed.