Thursday, July 23, 2009

Why Do Dogs Respond to Our Social Cues?

A focus of research on dog behavior has concerned the ability of dogs to respond to our social cues. In object choice tasks, a dog will have to decide which of two or more containers contains food. With certain controls, the dog unaided by a human will only perform at chance levels. If, however, a human points to the correct container, the dogs will much more likely go to it than the others. Even a human moving his eyes from the dog to the correct container and back and forth in this manner will help the dogs make the right choice, though not as often as pointing. Dogs will also choose the container a human is pointing at even if this is the wrong container, they’ve had a chance to smell the container with the food, and their noses should tell them to ignore the human’s pointing gesture. They trust us even when they shouldn’t. These findings, long known among canine behaviorists, lead to another question. Why do they follow our gestures when other animals, such as apes, don’t? Do they know we are trying to help them? Have they learned to trust us in the process of domestication? Pamela J. Reid of the ASPCA’s Animal Behavior Center in Urbana, Illinois, recently reviewed the literature on this topic, looking at the various hypotheses that have been propounded to explain why dogs read us so well. She distilled the conclusions of prior researchers down to four basic theories:

1. Dogs learn to respond to human social cues through basic conditioning processes.
2. Dogs reduced their fear of humans in the process of domestication and began to apply all-purpose problem-solving skills to their interactions with people.
3. Dogs’ co-evolution with humans equipped them with the cognitive machinery to respond to human social cues and understand our mental states (sometimes called a “theory of mind”).
4. Dogs are adaptively predisposed to learn about human communication gestures.

Reid herself favors the fourth explanation.

As to the first of the four theories, Reid notes that although dogs respond better to social cues after training, they perform significantly above chance even without prior experience with a pointing cue. Wolves raised the same way as dogs will not succeed as well as dogs in responding to pointing gestures.

Some researchers have argued that selection pressures placed on dogs for tameness and other desirable traits may have also been a stimulus for dogs to develop a specialized set of social skills. Dogs have learned to eat in the presence of humans and to accept restraint and in the process of domestication became expert readers of human social cues. Most (but not all) studies have found that dogs respond to social cues from humans far better than do wolves, their undomesticated ancestors. (Contrary research has recently been published by Monique Udell of the University of Florida and her colleagues.) Reid notes that Belyaev’s foxes, domesticated artificially, can follow pointing gestures as well as dog puppies of the same age, and are better at it than wild foxes. New Guinea Singing Dogs, similar to Australian dingoes, also perform of above chance, indicating that the ability to respond to human cues probably began in the earliest phases of domestication, since these unique dogs had only a rudimentary level of domestication before losing human contact. Perhaps dogs have learned to apply general rules of thumb such as “always approach the closest extension of the person,” or “always approach the person’s movement.” Such a mechanism would generally lead to the correct container in object choice tasks where a piece of food is placed in one of two or three containers and a human points to the correct container.

Reid attributes the third theory on the list above to the work of Adam Miklosi and Jozsef Topal and their colleagues, who argue that dogs and humans have evolved together to such an extent that human-like social skills have materialized in the dog in a process sometimes termed convergent evolution. This comes close to arguing that a dog understands that the human is trying to convey the location of food with a gesture. Miklosi has shown that dogs faced with an insoluble problem will look at a nearby human as though soliciting assistance. Reid argues that those scientists that take this “theory of mind” approach have found more sophisticated cognition in dogs than is justified by their research. It is, of course, likely that most pet owners would prefer to believe that there is a high level of human understanding in their pets.

Reid thinks the answer lies in the biological status of the dog as a scavenger, a niche that requires that an animal be acutely aware of other individuals in the social group that are also looking for opportunities to scrounge. They respond to our gestures towards food sources just as they respond to the other members of a pack that may be on the trail of a food source. This skill, combined with a tendency to learn, provided dogs with the skill to respond appropriately to our gestures, she argues. Reid admits that further research will be needed to narrow down the possible explanations as to why dogs are able to respond to our social cues. Pamela J. Reid, “Adapting to the Human World: Dogs’ Responsiveness to Our Social Cues,” 80 Behavioural Processes 325-333 (2009).

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