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We all seem to want to think our domestic dogs are intelligent. And in fact there have been quite a few studies evaluating dog intelligence to near that of a three year old child (minus the speech capability). However in this 2008 study researches proved that dogs along with humans and certain primates show envy/ jealousy

Furthermore, the experiment is believed to have shown for the first time a facet of dogs that is a very important part in the evolution of cooperation between dogs (and potentially their owners).

What the dog ENVY experiment was about

The dog experiment was set up to explore something called "inequity aversion".

"Inequity aversion is defined as partners resisting inequitable outcomes". In humans, it seems to be based on the simultaneous evaluation of their costs and gains compared with those of their partner. For instance in a working environment, when in theory you may have no specific emotion towards a colleague, doing more work and being rewarded less (wage, promotions, free time etc) can lead one to feel envy/ jealousy and then purposefully or otherwise under-performing - to show the manager your displeasure.

It has been suggested that comparing one's own payoff and effort during cooperation with those of others and reacting negatively to an unequal reward distribution in regard to the effort invested were crucial for the evolution of cooperation

Inequity and jealousy among Monkeys

To understand how this group created its experiment it is useful to look at previous research among animals on envy. Because it was originally speculated that other primates may show some forms of originally thought of Human forms of complex emotions, monkeys were tested for these traits.

Two types of primates were experimented with: capuchin monkeys (Cebus apella) and chimpanzees (Pan troglodytes). In these experiments "an animal had to exchange a token with the experimenter to obtain a food reward. They found that, if tested with a partner in visual contact, the monkeys responded negatively to unequal reward distributions, e.g., they refused participation if they witnessed a 'conspecific' (rival monkey) obtain a more attractive food reward for equal effort, an effect amplified if the partner received such a reward without any effort at all."

Previous knowledge of canid (dogs) cooperation in the wild

Cooperative actions have been seen in various canid groups before:  Cooperative hunting [e.g., wolves, Canis lupus; African wild dogs, Lycaon pictus] and cooperative rearing of pups [wolves, African wild dogs; mongoose, Suricata suricatta].

The previous belief has been that domestic dog–dog cooperation was impaired by the domestication process. There are many examples of dogs helping or cooperating with man with complex and elaborate cooperation with humans such as the gun dogs and assistant dogs, even customs and army dogs. However little research has been performed on domestic dog- dog cooperation, or its potential precursor - envy.

The premise of this experiment was that co-working / cooperation between dogs and humans often includes more than one dog interacting with humans such as in hunting. But it is thought that this is due to a dog's  high sensitivity to human behaviour, that cooperation is directed both toward them and to other humans.

Before the experiment: The researchers speculated that "dogs may respond differently when owners distribute rewards unequally among their dogs, and this includes asking for different efforts from the dogs for the same reward."

THE DOG ENVY EXPERIMENT

The experimenter requested the dogs to perform a certain action (instead of having to exchange a token for food, the dogs were asked to give their paw) to gain a food reward. The twist is that this action was performed in pairs of dogs.

The paw command was used since it is used by many trainers, and requires little effort for a dog to do.

For the main experiment itself, there were FOUR main situations they tested:

(i) the subject and the partner received the same low-value reward [baseline condition]

(ii) the subject received a lower-value reward than its partner

(iii) the subject received no reward whereas the partner received the low-value reward

(iv) both dogs received the low-value reward, but the partner did not have to give the paw to receive this reward

DOG ENVY EXPERIMENT RESULTS

In initial research they found that most dogs would stop giving the paw upon request after 15–20 times if not rewarded. The dogs show self interest here and are not just blindly following instructions.

The researchers found "differences in dogs tested without food reward in the presence of a rewarded partner compared with both a baseline condition (both partners rewarded) and an asocial control situation (no reward, no partner), indicating that the presence of a rewarded partner matters. Furthermore, (they) showed that it was not the presence of the second dog but the fact that the partner received the food that was responsible for the change in the subjects' behavior."

When the dogs were treated unequally for the same task (giving the paw) the unrewarded dogs refused earlier and hesitated longer to obey human commands. They also showed more stressed behavior.

Note that this was a scientific experiment with controls and a lot of statistical analysis to back up the findings, it is not merely 'observation'.

The dogs also exhibited a higher refusal rate, a "significantly longer hesitation, higher stress levels, and increased looking at the partner when the partner was rewarded and they themselves were not."

CONCLUSIONS

There are many conclusions that can be drawn from these studies. For instance in comparison to primate studies, the dogs showed no indication for sensitivity toward the quality of the food reward and the effort involved. Primates react to the quality of food, not just the presence/absence, and show more negative reactions than the dogs in this study. That is, the dogs refusal rates or delays in action did not change markedly to the size/ quality of the treat, just the presence or absence of the treat.

It is interesting that unlike humans and primates, the dogs never rejected food (even if they were rewarded unequally), ie the other dog didn't have to offer the paw for reward. "This means the dogs were only responsive to disadvantageous inequity aversion  and were not willing to pay a cost (of not eating a reward) by rejecting unfair offers (as is characteristic also of non-human primates), so there is a fundamental difference in the behavior of the primates and the dogs."

This research may also have consequences for rewarding dogs in a pack. It has always been suggested to reward the top dog first, but not rewarding all dogs may have a larger than expected effect on how likely dogs lower in the pack will respond to verbal recall instructions if they regularly miss out on a treat. As well as how they will behave differently to other dogs in the pack that receive rewards.

Article by Bruce Dwyer. If you wish to use any of this information please use a LINK reference to http://www.dogwalkersmelbourne.com.au

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Reference

The absence of reward induces inequity aversion in dogs - Friederike Rangea, Lisa Horn et al  -  de Waal, Emory University, Atlanta, GA, October 30, 2008