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, and dark-eyed juncos (Junco hyemalis), nonstoring birds, were compared in 2 operant delayed-matching-to-sample experiments. Subjects were required to remember a stimulus of a different color in a different spatial location on each trial. When spatial and color elements of the sample were placed in conflict on test trials in Experiments 1A and 1B, chickadees' first choices were controlled by the stimulus associated with the spatial location, but juncos' first choices were controlled by the spatial location and the color. In Experiment 2, each element was tested alone after exposure to the compound. Chickadees performed better on the spatial element than the color element, whereas juncos performed equally well on both elements. It is hypothesized that chickadees process spatial information at the expense of color, whereas juncos distribute their attention or memory, or both, more evenly across stimulus dimensions. This difference may be related to the chickadees' reliance on spatial information to find stored food.