In the process of domestication, it seems that dogs have become especially attuned to human communication. Does this mean they can cooperate with a human to solve a problem? And what if they need to cooperate with another dog instead? A study in press by Ostojić and Clayton investigates.
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The study is based on a “string task” in which two dogs (or a dog and a human) have to pull each end of a string in order to gain access to food that is otherwise out of reach on a platform.
The dogs were trained initially on a task they could solve on their own, because both ends of the string were close enough together. Some dogs opened their mouths very wide to get both ends in at once, while others used their paw to bring the ends closer together to make them fit in their jaw. When they pulled, a treat fell off the platform for them to eat.
Twenty-nine dogs were trained on this initial task. They included a number of search-and-rescue dogs, some with agility training, and pet dogs who had been trained in basic commands. They were a mix of breeds, including Golden retriever, Labrador retriever, and Parson Russell terrier, and of a range of ages.
The training for the study was very intense. Of the initial twenty-nine dogs, fifteen dogs could not complete the experiment because their owners did not have time, and three dogs did not take part because they were not interested in the initial task. This left eleven dogs that took part in the full experiment.
The dogs were from households with more than one dog, so that when they had to work in pairs it was with a dog they already knew.
The cooperative task was very similar to the initial string task, except that the two ends of the string were too far apart for one dog to solve it on their own. Each dog took part paired with another dog, and then again but paired with a human. When they set off from the starting point, each partner had to go to their end of the string, and when they pulled food fell off the platform. In the case of two dogs, two pieces of food fell off so that each got a reward.
In another version of the experiment, the scientists erected barriers so that one partner (dog or human) was delayed in reaching their end of the string. This meant the dog that was released normally had to wait for their partner to get to their end before they pulled the string; if they pulled it too much then the string would come all the way through and their partner would not be able to reach it.
Each trial lasted until either the problem was solved, the string was pulled so far through that the problem became unsolvable, or 2 minutes had elapsed. Each pair had up to sixty trials, or until they had solved it twenty times in total, to show they really had understood the problem and their success wasn’t a fluke.
Of the eleven dogs that had completed the initial training, all of them could solve the puzzle by cooperating with their partner. This was the case whether their partner was another dog or a human.
In the ‘delay’ condition, the non-delayed dog learned to wait for their canine partner. Sometimes they tugged a little bit on the string and then waited, before tugging hard once their partner was also tugging. There was hardly any difference between the ‘delay’ condition and the regular condition when the pair was made up of two dogs.
When the ‘delayed’ partner was a human, although dogs could still solve the problem, they did not do as well. This is probably because the length of the ‘delay’ was much greater; on average the human took an extra 13 seconds to reach their end of the rope, compared to just an extra 2s for the ‘delayed’ dogs. The task was therefore much harder with a human partner, since it required a greater degree of self-control.
The authors point out that the social cue – of their partner arriving at the rope – may not have been the only cue they used. They say the feeling of pressure on the rope may also have been a factor, as could the sight of the food moving closer to them when both partners had hold of the rope. However, a social cue was definitely part of the solution, because even on the very first ‘delay’ trial dogs waited longer to pull the string than on the previous regular trials. Future studies could use a design in which the social cue was the only one.
This study showed that once they had learned the puzzle during training on their own, dogs were able to learn how to solve the task when it required them to cooperate with a partner. This was the case whether the partner was canine or human. They could even still solve the problem when their partner was delayed in reaching the rope, and it required them to wait before taking action.
The reasons why dogs can do this are less easy to understand. The authors say, “In the case of cooperative problem-solving, it is not yet clear whether the dogs’ ability to solve such tasks arises from group hunting shown in other social carnivores and, in particular, in wolves, or from abilities evolved during domestication.”
Animal cognition research keeps finding ways to show just how clever dogs are. As ordinary dog owners, perhaps the thing to take from this is that our dogs might like more activities that use their brain power, whether it’s teaching tricks, agility, giving them problems to solve, or simply letting them enjoy their regular walks.
What do you do to keep your dog’s brain active?
ReferenceOstojic, L, & Clayton, N.S. (2013). Behavioural coordination of dogs in a cooperative problem-solving task with a conspecific and a human partner Animal Cognition DOI: 10.1007/s10071-013-0676-1