Cooperation among animals is sustainable only when rewards are fairly distributed. The phenomenon of inequity aversion—the negative reaction to unequal outcomes—has been documented in many species, including primates and dogs. However, it remains unclear whether dogs’ sensitivity to inequity stems from their social partner or from the human experimenter delivering rewards.
In this study published in Frontiers in Psychology, Désirée Brucks and colleagues tested 22 pairs of dogs in a cooperative task where they alternately pressed a buzzer to receive food rewards. The researchers compared two experimental conditions: one with a visible experimenter distributing rewards, and another where the experimenter was hidden, and rewards were dispensed mechanically.
The results revealed that dogs did not react to unequal rewards in either condition; however, in the experimenter-absent version, they displayed behaviors consistent with frustration and social facilitation rather than true inequity aversion. This suggests that the presence of a human experimenter plays a key role in activating social and emotional responses during cooperative tasks.
The authors propose that dogs may perceive fairness or unfairness primarily in the context of direct social interaction with humans, not simply when a resource is distributed unequally. Moreover, they note that subtle design details—such as whether rewards are delivered by hand or in separate bowls—can influence the perception of cooperation and competition.
These findings deepen our understanding of how human involvement shapes dogs’ social cognition, underscoring that fairness perceptions in dogs may rely as much on emotional engagement as on the rewards themselves.
Source: Brucks, D., Marshall-Pescini, S., Essler, J. L., McGetrick, J., Huber, L., & Range, F. (2017). What Are the Ingredients for an Inequity Paradigm? Manipulating the Experimenter’s Involvement in an Inequity Task with Dogs. Frontiers in Psychology, 8. Published February 28, 2017.
