Picture-object recognition in pigeons

Researchers in animal cognition frequently use pictures in place of real objects as stimuli in their studies although it is by no means obvious that an animal that is able to categorize pictorial stimuli understands what those pictures actually represent. Various nonhuman species have been shown able to recognize some correspondence between pictures and objects. Very rarely, however, it was possible to determine the mechanisms underlying such an ability. Actually, a subject may merely discriminate one or more visual features on a picture and recognize them in the real object (or vice versa). Positive picture-object (or object-picture) transfer would then be mediated by simple invariant 2D-characteristics, without recognition of the real 3D-object. But of course, such a mechanism is totally different from our perception of pictures as representations of the real world, which is based on an ability to recognize the relation between a picture and its 3D-referent on a level beyond that of mere feature discrimination ("representational insight"). The present project is aimed at investigating the mechanisms underlying picture-object recognition in pigeons, with possibilities ranging from lack of any picture-object associations at all to recognition by means of simple perceptual 2D-features up to representational insight and perception of true picture-object equivalence. To this end, an innovative approach (Complementary Information Procedure) will be applied that will allow for a clearer distinction between perceptual and cognitive factors than was the case in most previous studies. As determining how animals process pictures is an indispensable prerequisite to interpreting data obtained in all experiments that involve the presentation of pictorial stimuli the results of the present project will be relevant to a wide range of research concerned with animal visual cognition.