Have you ever noticed which direction your dog wags its tail towards? Most of us know some of the basic body language in a tail wag – happy, alert, afraid – but new research is showing that a wag to the right indicates happiness, and a swish to the left means nervousness – and other dogs know it.
“It is very well known in humans that the left and right side of the brain are differently involved in stimuli that invokes positive or negative emotions,” said Professor Georgio Vallortigara, a neuroscientist from the University of Trento in Italy. “Here we attempted to look at it in other species.”
In addition, he said that just as in humans, the right hemisphere of a dog’s brain is responsible for left-sided movement, and vice versa. To understand more about how dogs pick up on the subtle tail-wag cues to others, researchers and monitored the reactions of them watching films of other dogs.
“We presented dogs with movies of dogs – either a naturalistic version or a silhouette to get rid of any other confounding issues, and we could doctor the movement of the tail and present the tail more to the left or right,” Vallortigara explained.
When dogs saw an otherwise expressionless dog swish to the right, they remained relaxed. But when the tail waved to the left, their heart rates increased and they began looking anxious.
However, Vallortigara does not believe they are intentionally communicating through these movements, but have instead learned from their experiences of what kind of behaviors to look for following the wag, and what they should and should not worry about.
“If you have several meetings with other dogs, and frequently their tail wagging one way is associated with a more friendly behavior, and the right side is producing a less friendly behavior, you respond on the basis of that experience.”
While many considerate dog lovers already pay attention to their dog’s body language, Vallortigara’s team says this can better help owners, trainers and vets understand what dogs are feeling.
A team from the University of Lincoln in the UK discovered that dogs cock their heads to the right when they see a happy dog and to the left when they meet an aggressive dog.
“Dogs were more likely to approach a robot dog when its tail was made to wag left rather than right, rather than becoming anxious – the opposite way around to the [Italian] study,” said dog behavior expert John Bradshaw of the University of Bristol’s school of veterinary science.
He said the difference may be because dogs were not completely comprehending the robot dogs or the ones on film. Dogs’ interactions with real dogs will be more conclusive.
“While there is considerable evidence from many different mammals that the two sides of the brain are used for different purposes, much of the detail still has to be hammered out – and dogs are no exception,” he said. “However, given the ease with which their behavior can be recorded, it will probably not be long before we understand why their tails sometimes go one way, sometimes the other.”