Domestic dogs have evolved numerous adaptations for life alongside humans, yet a study from the University of Veterinary Medicine Vienna reveals they do not return food-based favors.
Researchers trained 37 domestic dogs to use a food vending machine by pressing a button, then separated the button and dispenser into distinct housings. In one setup, dogs paired with two unfamiliar humans: one helpful partner pressed the button to dispense food into the dog's enclosure, while the other did not. The setup was reversed, with the dog's button operating a dispenser in the human's enclosure. Results showed no significant difference in dogs' button-pressing for helpful versus unhelpful partners. Prior human behavior also did not influence dogs' interactions during free sessions post-testing.
Prior research demonstrates dogs can exhibit reciprocal altruism toward other dogs that helped them and distinguish cooperative from non-cooperative humans. However, this study found no evidence of dogs combining these traits to repay human kindness. The authors suggest dogs may lack this reciprocation tendency, or the setup failed to elicit it—perhaps because humans typically provide food, not receive it, or dogs missed the causal link between help and reward.
The authors conclude, “In our study, dogs were fed food from humans, but they didn't return the favor.”
