NY: Study: Dogs' tail-wagging patterns express 'feelings'
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Study: Dogs' tail-wagging patterns express 'feelings'
01:13 AM CDT on Tuesday, April 24, 2007
The New York Times
Every dog lover knows how a pooch expresses its feelings.
Ears close to the head, tense posture, and tail straight out from the body means "don't mess with me." Ears perked up, wriggly body and vigorously wagging tail means "I am sooo happy to see you!"
But there is another, newly discovered, feature of dog body language that may surprise attentive pet owners and experts in canine behavior. When dogs feel fundamentally positive about something or someone, their tails wag more to the right side of their rumps. When they have negative feelings, their tail wagging is biased to the left.
A study describing the phenomenon is in the March 20 issue of Current Biology. The authors are Giorgio Vallortigara, a neuroscientist at the University of Trieste in Italy, and two veterinarians, Angelo Quaranta and Marcello Siniscalchi, at the University of Bari, also in Italy.
"This is an intriguing observation," said Richard J. Davidson, a neuroscience researcher at the University of Wisconsin in Madison. It fits with a large body of research showing emotional asymmetry in the brain, he said.
Research has shown that in most animals, including birds, fish and frogs, the left brain specializes in behaviors involving what the scientists call approach and energy enrichment. In humans, that means the left brain is associated with positive feelings, like love, a sense of attachment, a feeling of safety and calm.
At a fundamental level, the right brain specializes in behaviors involving withdrawal and energy expenditure. In humans, these behaviors, like fleeing, are associated with feelings like fear and depression.
Dog tails are interesting, Davidson said, because they are in the midline of the dog's body, neither left nor right.
Vallortigara and his colleagues recruited 30 family pets of mixed breed that were enrolled in an agility training program. The dogs were placed in a cage equipped with cameras that precisely tracked the angles of their tail wags. Then they were shown four stimuli through a slat in the front of the cage: their owner; an unfamiliar human; a cat; and an unfamiliar, dominant dog.
When the dogs saw their owners, their tails all wagged vigorously toward the right side of their bodies, Vallortigara said. Their tails wagged moderately and more to the right, when faced with an unfamiliar human. Looking at the cat, the dogs' tails again wagged more to the right but in a lower amplitude.
When the dogs looked at an aggressive, unfamiliar dog – a large Belgian shepherd Malinois – their tails all wagged to the left side of their bodies.
Thus when dogs were attracted to something, including a benign, approachable cat, their tails wagged right; and when they were fearful, their tails went left, Vallortigara said.
It suggests that the muscles in the right side of the tail reflect positive emotions while the muscles in the left side express negative ones.
