July 24 (HealthDay News) -- What's in a bark? A new study suggests that 6-month-old babies know the answer.
Researchers found that most infants who were tested could figure out that an aggressive bark goes with an angry-looking dog. They also seemed to know that friendly-looking pooches voice their feelings in a different way.
The babies managed to do this even though they weren't very familiar with dogs.
It's not clear whether the babies actually know that a dog baring its teeth is a sign of trouble, but they're showing a level of sophistication regarding how dogs reveal their emotions, said study author Ross Flom, an associate professor of psychology and neuroscience at Brigham Young University in Provo, Utah.
"We think babies have a broad-based set of abilities and skills when they enter the world," he said. "And those become broadened and honed based on the individual experiences in their lives."
Flom spends his time studying how babies perceive emotions, and previously found that they can tell the difference between upbeat and gloomy music.
In the new study, Flom and his colleagues recruited 128 infants and toddlers, almost all of whom were white. All of the participants had little or no exposure to dogs during their brief lives.
The researchers showed the babies video stills of aggressive and non-aggressive dogs, and watched what they did when they heard sounds of barking.
The study results appear in the July issue of Developmental Psychology.
The researchers believe that they can glean whether a baby is making a connection between two things by monitoring how long they look at a picture. In this case, 6-month-old babies were more likely to look longer at the picture of a canine expression that matched the bark.
Only about 15 percent of the babies spent more time looking at the wrong dog picture or looked equally at both, Flom said.
Older babies -- at 12, 18 and 24 months -- were likely to look at the correct dog, but for just a flicker of time, Flom said, and then look around the room or equally between the video stills.
While some have interpreted this to mean they can't distinguish the correct picture, Flom said it's actually a sign that "the task is almost too easy for them."
The study didn't examine what the babies actually perceived about the barks and the canine expressions. No one knows if they're aware that a normal-looking dog is a better prospect for playtime than one that looks -- and sounds -- like it wants to take a bite out of the nearest leg.
Still, it's "remarkable" that babies that aren't exposed to dogs can figure out how to link their barks to their faces, Flom said. That means they can connect audio and visual cues, he said.
As for the future, researchers are exploring how humans relate to dogs, which have a long history of interacting with people, and wolves, which don't.
Over time, Flom said, dogs and humans have learned how to communicate with each other.
And, of course, each gets what they want from the other, whether it be the newspaper or a long back scratch.
SOURCES: Ross Flom, Ph.D., associate professor, psychology and neuroscience, Brigham Young University, Provo, Utah; July 2009 Developmental Psychology