Dog owners know the difference when they hear happy barks from their pets versus unhappy ones. Now, scientists have shown that it works both ways. Dogs really do understand their human’s emotions by hearing their voice, much like a person can hear a friend on the phone and know if they are sad or happy. A new study confirmed what many dog owners have long claimed – that dogs and humans think alike. Canines, like people, pick up on emotional cues and are sensitive to speech tones. Both species even use the same part of their brain to process the sounds.
The study, published in the Feb. 20 issues of Current Biology, looked at how dogs react to auditory cues from humans. The results show that both use similar brain mechanisms to process emotional cues. Researchers suspect the brain area responsible for voice and sounds in both species evolved 100 million years ago, when the dogs and humans shared common ancestors. It shows why to the two species seem to communicate with each other and share a similar social environment, according to the study’s lead author, Attila Andics, a Hungarian Academy of Sciences neuroscientist at Budapest’s Eötvös Loránd University.
To find out if dogs get social cues from human voices, Andics and colleagues used functional magnetic resonance imaging (fMRI) to scan canine and human brains to see how they process different voices, barks, and natural noises. In humans, the voice area of the brain, help people recognize a speaker’s identity and pick up on the voice’s emotional content. The researchers wanted to see if dogs’ brains had voice areas like humans and other primates.
To conduct the study, the scientists trained 11 dogs to enter, lie down and remain still in the fMRI machine. The researchers then used the scanner to analyze the brain activity of the dogs as well as humans to see if they think alike. They studied the reactions from both species as they heard 200 human and dog sounds, including crying, playful barking and laughing.
Both dogs and humans responded strongest to noises from their own species. In addition, the brains scans showed they processed emotionally laden sounds in comparable ways. For example, both species showed greater activation of the primary auditory cortex in the brain when hearing happy sounds, like a baby’s giggle. When the same part of the brain is used for unhappy sounds, the reaction was not as strong in both species.
One area that dog and human brains showed differences in reaction involved non-vocal noises. The researchers discovered that dogs respond more strongly to environmental sounds, such as a car engine, than to voices. Forty-eight percent of their auditory brain regions reacted versus humans, who only reacted using 3 percent of auditory brain region.
Andics pointed out that the discovery of voice areas in dog brains shows a common evolution. The scientist noted that it is probably not just dogs and humans that think alike; this function is probably shared with other mammals, too.
By Dyanne Weiss