Pet dogs prefer to work alone than to engage in a challenging cooperative task with conspecifics.

Understanding the role of a partner is key to effective human cooperation. While we know that non-human animals extensively cooperate with each other, how well they understand the role of their partner is unclear. This has been explored using economic games, yielding mixed results. A previous study showed that dogs understand the role of their human partner in an economic game setting, adjusting their behavior according to the partner's choices, but there are no clear results when it comes to dog conspecific cooperation. In this study, we tested pairs of pet dogs in the stag hunt game. In the typical payoff group, dogs had the option to perform a more challenging, cooperative action for a higher reward or work individually for a lower one. To test for a potential effect of motivation for the high value reward, we had a same reward group where cooperation or individual work led to the same reward. Dogs had minimal training and exposure to the contingencies of the game. Dog pairs from both groups only coordinated their choice on the cooperative action in 5% of the trials. Accordingly, we found that dogs were generally more likely to work individually, regardless of their partner's actions and obtainable rewards. In the typical payoff group, dogs initially showed a greater tendency to cooperate during the first session, but this declined quickly, with dogs from pairs ultimately working alone. The low success on the cooperative apparatus was likely due to dogs not investing sufficient effort to find the solution by trial-and-error. This could be due to the fact that the high-quality reward was not good enough to invest that extra effort or a preference of dogs to work alone if given the choice. Overall, our results showed that dogs did not choose to cooperate with conspecifics, in contrast to their demonstrated success in interspecific contexts. We discuss how cooperation is potentially sensitive to contextual and social constraints rather than widespread.