A new study reveals that the direction a dog's tail wags in reveals more about their emotions than previously thought. Scientists determined that if a dog's tail wags to the right they are happy; if it wags to the left, they could be scared.
The scientists involved in the study concluded that dogs use their tails to deliver subtle signals to other dogs that are hidden from humans and mean more than simply "I'm happy" or "I'm pleased to see you".
An Italian team of researchers at the University of Trento carried out the study, which involved 43 healthy dogs of various breeds. The scientists showed dogs videos of other dogs and monitored their heart rate. The video clips either showed a dog with his tail wagging more to the right or more to the left. Some videos blanked out the dog's features (except for the tail) so as to not have facial expressions influence the dogs in the study.
When dogs saw a video of a dog with his tail wagging more to the left their heart rates went up and they began to look anxious. When the dogs were shown video of tail wagging more to the right they remained calm and relaxed.
The scientists also correlated the dogs' reactions with their brain activity. Right wagging activated the canine brain's left hemisphere whereas left wagging activated the canine brain's right hemisphere.
Scientific research into animal behavior has indicated that the left brain specializes in positive feelings, serenity and calm. Contrast this with the right brain, which specializes in behaviors associated with fear and depression.
Dr. Giorgio Vallortigara, who led the research, does not think the dogs are consciously communicating their emotions. Rather, he thinks the dog's brain is wired to respond to the movement of the wagging tail.
"We don’t know exactly if the receiver [dogs in study] is consciously picking up the signal, but I think it is more likely not to be. Instead it is likely to be because the movement is activating either the right or left hemisphere of the brain by attracting their attention to the left or right side of their vision."
The tail-wagging difference appears to be one way that dogs gauge how other dogs will respond to them and aggressive, unfamiliar dogs caused left-biased tail wagging.
Dr. Vallortigara says his research could have practical applications that could be helpful to dog guardians and veterinarians.
The report came out in the journal of Current Biology.
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