Functional categorization of objects and of their pictures in baboons

Abstract

Baboons were trained and tested on the natural category of food versus nonfood with real objects using an adapted version of a WGTA. Four subjects were first trained to categorize two objects, one food and one nonfood; then 80 other objects (40 food and 40 nonfood) were presented and categorical response to each object was recorded. The baboons showed a good and rapid transfer of their categorical abilities to the novel items. In subsequent experiments, two subjects were trained with cut-out photos or with whole photos (i.e., pictures with background) of one object in each of the previously learned category and then tested with a subset of photos of the objects used in the first experiment. After training with one pair of pictures, categorical transfer was high in both baboons for cut-out photos but one subject only correctly categorized whole photos of the objects. Results of these experiments and of additional control situations involving various modes of picture presentations further demonstrated the abilities of the baboons to relate real objects with their pictorial representations.