The effect of distinctive parts on recognition of depth-rotated objects bypigeons (Columba livia) and humans

To explore whether effects observed in human object recognition represent f undamental properties of visual perception that are general across species, the authors trained pigeons (Columba livia) and humans to discriminate bet ween pictures of 3-dimensional objects that differed in shape. Novel pictur es of the depth-rotated objects were then tested for recognition. Across co nditions, the object pairs contained either 0, 1, 3, or 5 distinctive parts . Pigeons showed viewpoint dependence in all object-part conditions, and th eir performance declined systematically with degree of rotation from the ne arest training view. Humans showed viewpoint invariance for novel rotations between the training views but viewpoint dependence for novel rotations ou tside the training views. For humans, but not pigeons, viewpoint dependence was weakest in the 1-part condition. The authors discuss the results in te rms of structural and multiple-view models of object recognition.