Rivalry and Decision-Making in Dogs

The relationship between two household dogs affects their decisions, according to new research.

Two dogs sleeping on top of each other on a bed

By Zazie Todd, PhD

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If you have more than one dog, you might have noticed that if one goes over to sniff a particular spot, sometimes the other dog will also go over there. It’s called local enhancement, in which one dog (we call them the ‘demonstrator’) draws the other dog’s attention to a specific location. It’s a type of social learning that is found in many species.

Dr. Christy Hoffman and Dr. Malini Suchak (Canisius College) investigated whether local enhancement is affected by rivalry between dogs that live in the same household. The dogs were classed as either low- or high-rivalry based on their owners responses to questions on the C-BARQ.

The dog rivalry questions assessed how likely the dog is to be aggressive towards the other dog in the household, or to be aggressive when the other dog approaches when they are sleeping, eating, or playing with a toy.
After conducting two experiments, the scientists found that,
“When allowed to make a decision quickly, low-rivalry dogs were more heavily influenced by dog and human demonstrators than high-rivalry dogs, but this difference between high-rivalry and low-rivalry dogs disappeared when dogs were forced to wait 5 s before approaching the plates. Because the demonstrator and observer dogs lived together in the same household, the pre-existing social relationship between the dogs is particularly likely to have influenced how attentive they were to the dog demonstrator dog and, as a result, their performance on the task.”
Dogs from two-dog households were tested in their own home. Within a pair, the dogs did not necessarily have the same rating for rivalry (i.e. it could be two high, two low, or one high and one low-rivalry dog).

Fifty dogs took part in the first study. The experimental set-up involved two paper plates on the floor, to which a research assistant added some food. Under the watchful eye of one dog, the other dog (the ‘demonstrator’) was allowed to walk up to one of the plates, scoff the food, and was taken out of the room.

Then the dog was allowed to approach one of the plates. Would they go to the – now empty – plate the demonstrator dog had gone to, or would they go to the plate with the food on?

The effect of rivalry between dogs on their behaviour
Photo: Dima Zverev; top, Bill Anastasiou (both Shutterstock.com)

It’s worth noting first of all that the human holding the dog’s leash had their eyes closed and faced the other way so they would not see which plate the demonstrator dog went to (and so could not influence the dog).

And also – very importantly – whichever plate the dog chose to approach, the empty one or the one with food on, they were allowed to eat the food that was left.

The results showed there was an effect of rivalry. Dogs who scored low on rivalry were more likely to go to the empty plate than those who were rated as high-rivalry.

Interestingly, this was also the case in a human control condition, in which only one dog was in the room, and the human research assistant removed the food from one of the plates.

The scientists say,
“These results suggest that low-rivalry dogs, as compared to high-rivalry dogs, may be more susceptible to local enhancement and, therefore, more likely to copy other dogs’ and humans’ actions.”
However, when there was a 5 second delay before the dog could choose which plate to go to, then the low-rivalry dogs were also more likely to go to the plate with food on instead of the empty plate.

The delay condition always happened after the condition in which dogs could make an immediate choice. This meant it was possible, even though the dogs got the food anyway, they had learned to get the food faster.

So the scientists conducted a second experiment with a new set of 24 dogs. In this experiment there was always a 5-second delay before the dog could go to one of the plates.

This time, rivalry was not linked to any effects; both low- and high-rivalry dogs were more likely to go to the plate with food on. This suggests that it is in fact the delay that caused the local enhancement effect for low-rivalry dogs to disappear.

The researchers made a video about their research that explains what they found:

Of course, we cannot say what was going on inside the dogs’ heads when they took part. But it seems that for low-rivalry dogs, the lack of food on the plate did not affect their decision to go to that plate first. Perhaps for the high-rivalry dogs, because they were not as tolerant of the other dog, they did not pay as much attention to where it went.

One of the nice things about this study is that it looked at how dogs behaved in a situation with another dog they were very familiar with. The scientists say,
“understanding the nature of established dog–dog relationships needs more attention from researchers. This study constitutes a first step toward better understanding that dynamic.”
You can read my interview with Dr. Christy Hoffman about her research, foster failures, and what makes Anthrozoology so exciting. You can also follow the Canisius Canine Research Team on Facebook.

If you liked this post, check out my award-winning book Wag: The Science of Making Your Dog Happy. Modern Dog magazine calls it "the must-have guide to improving your dog's life."

Zazie Todd, PhD, is the award-winning author of Wag: The Science of Making Your Dog Happy and Purr: The Science of Making Your Cat Happy. She is the creator of the popular blog, Companion Animal Psychology, writes The Pawsitive Post premium newsletter, and also has a column at Psychology Today. Todd lives in Maple Ridge, BC, with her husband, one dog, and two cats. 

Useful links:

Hoffman, C. L., & Suchak, M. (2017). Dog rivalry impacts following behavior in a decision-making task involving food. Animal Cognition, 1-13.

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