Researchers reporting in the journal Current Biology have discovered that dogs communicate more information about their feelings with their tails than was previously thought.
Dogs recognize and respond differently when their fellow canines wag to the right than they do when they wag to the left. Image credit: Marcello Siniscalchi et al.
The results show that dogs, like humans, have asymmetrically organized brains, with the left and right sides playing different roles.
In a previous study, the same team found that dogs wag to the right when they feel positive emotions and to the left when they feel negative emotions. That biased tail-wagging behavior reflects what is happening in the dogs’ brains.
In the new study, the researchers showed dogs videos of other dogs with either left- or right-asymmetric tail wagging. When dogs saw another dog wagging to the left, their heart rates picked up and they began to look anxious. When dogs saw another dog wagging to the right, they stayed perfectly relaxed.
“The direction of tail wagging does in fact matter, and it matters in a way that matches hemispheric activation,” said co-author Dr Giorgio Vallortigara from the University of Trento.
“In other words, a dog looking to a dog wagging with a bias to the right side – and thus showing left-hemisphere activation as if it was experiencing some sort of positive/approach response – would also produce relaxed responses.”
“In contrast, a dog looking to a dog wagging with a bias to the left – and thus showing right-hemisphere activation as if it was experiencing some sort of negative/withdrawal response – would also produce anxious and targeting responses as well as increased cardiac frequency. That is amazing, I think.”
The scientists don’t think that the dogs are necessarily intending to communicate those emotions to other dogs.
Rather, the bias in tail wagging is likely the automatic byproduct of differential activation of the left versus the right side of the brain. But that’s not to say that the bias in wagging and its response might not find practical uses; veterinarians and dog owners might do well to take note.
“It could be that left/right directions of approach could be effectively used by vets during visits of the animals or that dummies could be used to exploit asymmetries of emotional responses,” Dr Vallortigara said.
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Bibliographic information: Marcello Siniscalchi et al. 2013. Seeing Left- or Right-Asymmetric Tail Wagging Produces Different Emotional Responses in Dogs. Current Biology, 23, 1–4; doi: 10.1016/j.cub.2013.09.027
