Welcome sign: A wag to the left is friendlier than one to the right
Everyone knows that if a dog’s ears are up and its tail is wagging vigorously, it is definitely pleased to see you.
Now, scientists using a robot have found that the way dogs use their tails is more subtle than we thought and that dogs that wag them to the left may be more friendly.
The animal psychologists discovered that when real dogs approached a life-sized black Labrador with a mechanical tail, they were less wary of it when it was wagging its tail on the left side of its body.
When the robot’s tale wagged to the right side, far fewer dogs approached it in a confident manner.
In the experiments, the researchers used a model with black synthetic fur covering a wire-framed body.
A small motor allowed the tail to be manipulated by a hand-held remote control.
More than 500 dogs were filmed as they approached the model in a public park.
In the study, published in the journal Laterality, the researchers looked in particular at whether the dogs were hesitant or not as they walked up to the model, as stopping or pausing can be a sign of lack of confidence, doubt or fear. In the first batch of the experiments, 56 per cent of the animals approached the model without hesitation when the tail was wagged to the left, but only 21 per cent had such a direct approach when it went to the right.
When the researchers excluded incidents where owners were present and may have influenced the behaviour of their pets, the results were similar: 41 per cent of the dogs approached continuously when the tail was wagging to the left, while only 28 per cent did so when it was on the right.
The researchers, from the University of Victoria in Canada, said they did not know whether the dogs’ behaviour was the result of experience or an inherited predisposition.
But they warned that the results suggested that the controversial practice of tail docking in some breeds could disrupt communication between animals.
Animal psychologist Roger Mugford said it added to growing evidence that dogs were even more sophisticated communicators than animals more closely related to man such as monkeys.
He said: ‘It is ground-breaking stuff. We know that dogs, in a sense, have language, but it is more complicated because it is not just them wagging their tails, but also giving out chemical displays.’
Surrey-based Dr Mugford said the research reinforced earlier studies suggesting that dogs, like humans, had a left-side bias.
He explained: ‘If you are going to present a signal to a dog, it is sensible to put it on your left-hand side because that is where dogs, unusually among other species of animals, tend to look.
‘It is another example of the similarity between dogs and humans. They are a lot more human than we give them credit for.’