What or where? The meaning of referential human pointing for dogs (Canis familiaris)

Dogs have a unique capacity to follow human pointing, and thus it is often assumed that they can comprehend the referential meaning of such signals. However, it is still unclear whether dogs perceive human directional gestures as signals referring to a target object (indicating what to manipulate) or a spatial cue (indicating where to do something). In the present study, we investigated which of these alternative interpretations may explain dogs' responses to human pointing gestures in ostensive communicative and nonostensive cuing contexts. To test whether dogs select the cued object or the cued location, subjects were presented with 2 alternative object-choice trials. An experimenter first attracted the attention of the dog either by calling the dog's name and looking at it (ostensive condition, n = 24) or by clapping the hands (nonostensive condition, n = 24) then pointed at 1 of 2 different toy objects. Subsequently, the experimenter switched the location of the 2 target objects in full view of the dogs by grasping the objects and making a 180° turn. Dogs were then allowed to choose between the 2 objects. In the ostensive condition, dogs showed a significant bias toward the cued location compared with the nonostensive condition in which they performed at chance. These results suggest that pointing refers to a direction or location for dogs, but only if they are addressed with ostensive cues that indicate the communicative intention of the signaler.