Pointing changes the meaning of human vocal tone in a dog's mind
Dogs can use human social cues like pointing to find hidden food, but can they use only our tone of voice to make choices? Researchers at the University of Puget Sound in Tacoma, Washington gave dogs an opportunity to choose between two buckets full of treats after they had been associated with positive or negative “Ooo” sounds, or a breath sound as a control. Dogs preferred to choose the box associated with the positive vocal tones, indicting they can use vocal tones informatively. However, when the same procedure was completed again with the addition of pointing cues, dogs chose the container being pointed at more often regardless of emotion. Interestingly though, the dogs had the strongest preference for pointing and negative vocal tones.
Dogs have been shown to use human social cues like pointing to find hidden objects or make a choice between two objects. Dogs can do this when additional information like facial expression, tone of voice, or words are presented, or when the pointing cues are presented alone. Researchers at the University of Puget Sound in Tacoma, Washington wanted to determine if dogs could use human tone of voice alone to make choices between two objects. They first made sure the dogs understood there were treats in both containers, and that the dogs would take treats from the containers, in a pretesting procedure.
The dogs then began the first experiment, where their owners held them as they watched the experimenter cue the containers. As the dog watched, the experimenter called the dog’s name and told it to look as they shuffled the treats in the container and then placed them on the ground. Once they had the dog’s attention on the containers, the experimenter then cued one container (with negative, positive, or breath sounds as a control), stood up, then cued the other container with a different vocal tone or breath. For example, one might be cued negative, while the other cued with a breath sound. Each dog experienced the following cue pairings: Negative/Positive, Positive/Breath, and Negative/Breath, totaling 12 choice trials, or 4 trials with each cue pairing. Once the containers had been cued, the experimenter said “OK!” and the dog was released to make a decision about which container to investigate. The results from this experiment indicated no difference when choosing between containers associated with negative/breath or negative/positive, but the dogs preferred the positively associated container when compared to the breath container. The researchers determined this behavior as evidence that dogs have the ability to use vocal tone information alone to make choices.
They ran an additional experiment, adding point cues to one container, to determine if the body language cue of pointing would change the dog’s response behavior. In the presence of the point cue, dogs chose the container the experimenter had pointed at more often no matter what the associated emotion was. However, the combination the dog’s chose most was negative vocal tone plus pointing. This result is interesting – the vocal tone associated with choice preference flipped in the presence of the pointing cue.
Why is that? The researchers suggested when the highly useful cue of pointing is added to vocal tones, the tone shifts from informative to instructive. Meaning, when we point at something, then vocalize or talk, dogs likely associate this vocalization with an instruction or command rather than informative communication such as telling them they have a new toy. With this line of thought, the negative voice tone would need to be considered the instructional vocal tone. As dog owners, many of us may use negative vocal tone as an instructional or training tool to deter unwanted behavior, providing dogs with the opportunity to learn to associate negative tone of voice as instructional in the presence of certain body language cues. Other times, we might talk to our dogs in positive vocal tones during play, or times where the dog is permitted free-choice. In those situations, dogs have the opportunity to learn that positive vocalizations in the absence of any specific body language cues can provide informative information about their environment.
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Where to find the article: Colbert-White, E.N., Tullis, A., Andresen, D. R., Parker, K. M., Patterson, K. E. (2018). Can dogs use vocal intonation as a social referencing cue in an object choice task? Animal Cognition, 21, 253-265. https://doi.org/10.1007/s10071-018-1163-5
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