Amodal completion by baboons (Papio papio): contribution of background depth cues.

Four baboons (Papio papio) were tested in a computerized two-alternative forced choice task in which partially occluded graphic stimuli were shown either on linear perspective backgrounds depicting a corridor or on uniformly black backgrounds. The results indicated that baboons complete partly occluded stimuli and that amodal completion is facilitated by the display of pictorial background depth cues. Inter-individual differences emerged in the ability to extrapolate three-dimensional information from two-dimensional visual information.