An experiment involving dog treats suggests our canine pals may understand the difference when a human withholds a treat by accident and when they do so on purpose. But don't press your luck.



Accidentally stepping on your dog is the worst, especially if they're little. The dog yelps, you apologize, but can dogs really understand the difference between a person doing something on purpose and doing it by accident? Well, a new set of experiments suggests that maybe dogs can. NPR's Nell Greenfieldboyce reports.

NELL GREENFIELDBOYCE, BYLINE: Have no fear. These experiments did not involve stepping on dogs. They did involve giving dogs treats and sometimes withholding those treats. Britta Schunemann is now at Harvard University. She worked on this study in Germany.

BRITTA SCHUNEMANN: OK, so the basic idea of the experiment was whether dogs understand whether a human intentionally withheld food or unintentionally withholds food.

GREENFIELDBOYCE: She says pet owners brought 51 dogs to the Max Planck Institute for the Science of Human History. There, the dogs were taken to a glass partition. It looked like a window set up in the middle of a big room. To get a treat, the dogs had to stand on one side of it while a stranger sat on the other side and passed the food through a hole.

SCHUNEMANN: The idea was just to establish we feed you through that petition. So that's what's happening here today.

GREENFIELDBOYCE: Once the dogs had that down, the experiment could truly begin.

SCHUNEMANN: We interrupted this established pattern by suddenly withholding the treats.

GREENFIELDBOYCE: The treats were sometimes withheld by accident. Schunemann says the experimenter would pretend to clumsily drop the food.

SCHUNEMANN: So she tried to administer the treat, but it just fell down, and she tried again and again.

GREENFIELDBOYCE: Other times, when the experimenter tried to pass the treat through the partition, the whole was suddenly closed.

SCHUNEMANN: So even though she wanted to give the rewards, she couldn't do it anymore because there was just no way.

GREENFIELDBOYCE: And then occasionally the dog didn't get a treat because the experimenter withheld it on purpose. She would let a dog see a treat but then pull it back, basically saying, uh, uh, uh. Now, every single time the dog didn't get food for whatever reason, the treat ended up on the floor by the experimenter's seat. The dog could see it through the glass and could walk around the partition and get it. That is just what the dogs did. But when the food had been withheld deliberately, the dogs were slower to go for it.

SCHUNEMANN: Dogs were more hesitant and waited longer to approach the food that they weren't supposed to have because it was withheld intentionally.

GREENFIELDBOYCE: The researchers think this shows that the dogs understood that this denial of food was on purpose. The results appear in the journal Scientific Reports. Clive Wynne, however, is skeptical. He didn't work on this study. He directs the Canine Science Collaboratory at Arizona State University.

CLIVE WYNNE: I'm not convinced. I think it's a fascinating question, but it's a tremendously difficult question to get a handle on.

GREENFIELDBOYCE: He believes dogs have an amazing ability to emotionally bond with humans. But he doubts they care about our intentions, especially when food is on the floor.

Nell Greenfieldboyce, NPR News. Transcript provided by NPR, Copyright NPR.