MATCHING LOCATION AND COLOR OF A COMPOUND STIMULUS - COMPARISON OF A FOOD-STORING AND A NONSTORING BIRD SPECIES

Black-capped chickadees (Pants atricapillus), birds that store food, a nd dark-eyed juncos (Junco hyemalis), nonstoring birds, were compared in 2 operant delayed-matching-to-sample experiments. Subjects were req uired to remember a stimulus of a different color in a different spati al location on each trial. When spatial and color elements of the samp le were placed in conflict on test trials in Experiments 1A and 1B, ch ickadees' first choices were controlled by the stimulus associated wit h the spatial location, but juncos' first choices were controlled by t he spatial location and the color. In Experiment 2, each element was t ested alone after exposure to the compound. Chickadees performed bette r on the spatial element than the color element, whereas juncos perfor med equally well on both elements. It is hypothesized that chickadees process spatial information at the expense of color, whereas juncos di stribute their attention or memory, or both, more evenly across stimul us dimensions. This difference may be related to the chickadees' relia nce on spatial information to find stored food.