Can't get your dog to respond to a command? Try rewarding your pet with a tummy rub when it final complies, say researchers who've found dogs prefer hands-on petting to verbal praise.

U.S. behavioral scientists, testing whether vocal praise or petting is preferred by our furry friends, found that dogs love to be petted -- and they don't care by whom, owner or stranger.

In fact, they said, the only thing dogs like more than being petted is being fed -- a fact any dog owner has likely already figured out.

In the journal Behavioral Processes, the researchers describe an experiment in which 42 dogs, both pets and shelter dogs, interacted one at a time with two people, one of whom petted the animal while the other offered verbal praise and encouragement.

The result? Dogs uniformly preferred the people who were petting them.

That came as a surprise to some of the researchers who are themselves dog owners.

"I spend half my day talking to my dog," says study author Clive Wynne, head of Arizona State University's Canine Science Collaboratory. "She always looks like it's valuable to her. It's quite a shock to discover that what we say to dogs doesn't seem to be rewarding to them after all."

In another experiment, dogs -- again, both shelter dogs and pets -- were put in a room with a person who over multiple sessions with the dog either petted it, offered vocal praise, or performed no interaction at all with the animal.

Again, the researcher found, petting was preferred; and in fact, the dogs demonstrated as little interest in the vocal praise as they did in receiving no interaction of any kind.

"I was surprised that when only one alternative was available, dogs still did not engage with the human for vocal praise," says study co-author Erica Feuerbachet, who performed the research during her doctoral studies at the University of Florida.

A clue to why canines might prefer petting is suggested by previous studies that found dogs' blood pressure and heart rate were lowered during petting from humans, the researchers said.

This mirrors a number of studies in humans that have suggested human health can be helped through human physical contact, they added.

Wynne, for his part, says the findings haven't stopped him from having conversations with his dog.

"I just recognize better that I'm doing it more for my benefit than for hers," he says. "And this study doesn't say that you can't train your dog to recognize vocal praise. If vocal praise is paired with rewards that dogs do care about (petting, food, etc), then they can learn to value it."

So keep on saying "Good dog!" Just know that combining that with a tummy rub is the way to go, he says.