Many dog owners will swear their pups are up to something when out of view of watchful eyes. Shoes go missing, couches have mysterious teeth marks, and food disappears. They seem to disregard the word "no."
Now, a new study suggests dogs might understand people even better than we thought. (Related: "Animal Minds.")
The research shows that domestic dogs, when told not to snatch a piece of food, are more likely to disobey the command in a dark room than in a lit room.
This suggests that man's best friend is capable of understanding a human's point of view, said study leader Juliane Kaminski, a psychologist at the U.K.'s University of Portsmouth.
"The one thing we can say is that dogs really have specialized skills in reading human communication," she said. "This is special in dogs." (Read "How to Build a Dog.")
Kaminski and colleagues recruited 84 dogs, all of which were more than a year old, motivated by food, and comfortable with both strangers and dark rooms.
The team then set up experiments in which a person commanded a dog not to take a piece of food on the floor and repeated the commands in a room with different lighting scenarios ranging from fully lit to fully dark.
They found that the dogs were four times as likely to steal the food—and steal it more quickly—when the room was dark. (Take our dog quiz.)
"We were thinking what affected the dog was whether they saw the human, but seeing the human or not didn't affect the behavior," said Kaminski, whose study was published recently in the journal Animal Cognition.
Instead, she said, the dog's behavior depended on whether the food was in the light or not, suggesting that the dog made its decision based on whether the human could see them approaching the food.
"In a general sense, [Kaminski] and other researchers are interested in whether the dog has a theory of mind," said Alexandra Horowitz, head of the Dog Cognition Lab at Barnard University, who was not involved in the new study.
Something that all normal adult humans have, theory of mind is "an understanding that others have different perspective, knowledge, feelings than we do," said Horowitz, also the author of Inside of a Dog.
Smarter Than We Think
While research has previously been focused on our closer relatives—chimpanzees and bonobos—interest in dog cognition is increasing, thanks in part to owners wanting to know what their dogs are thinking. (Pictures: How smart are these animals?)
"The study of dog cognition suddenly began about 15 years ago," Horowitz said.
Part of the reason for that, said Brian Hare, director of the Duke Canine Cognition Lab and author of The Genius of Dogs, is that "science thought dogs were unremarkable."
But "dogs have a genius—years ago we didn't know what that was," said Hare, who was not involved in the new research. (See pictures of the the evolution of dogs, from wolf to woof.)
Many of the new dog studies are variations on research done with chimpanzees, bonobos, and even young children. Animal-cognition researchers are looking into dogs' ability to imitate, solve problems, or navigate social environments.
So just how much does your dog understand? It's much more than you—and science—probably thought.
Selectively bred as companions for thousands of years, dogs are especially attuned to human emotions—and, study leader Kaminski said, are better at reading human cues than even our closest mammalian relatives.
"There has been a physiological change in dogs because of domestication," Duke's Hare added. "Dogs want to bond with us in ways other species don't." (Related: "Dogs' Brains Reorganized by Breeding.")
While research reveals more and more insight into the minds of our furry best friends, Kaminski said, "We still don't know just how smart they are."