A dog can tell when another pooch is wagging its tail to the left or right and responds differently when the wag goes one way or the other, a new study shows.
Previous research by the same team showed that dogs wag to the right when they feel happy (seeing their owners, for example) and to the left when they're upset (seeing an unfriendly dog, for example). That means that left-brain activation produces a wag to the right and right-brain activation results in a wag to the left.
This new study examined whether the direction of tail wagging means anything to other dogs and found that it did, according to the study published in the journal Current Biology.
How the study was done
The researchers monitored dogs as they watched videos of other dogs wagging their tails either left or right. When dogs saw another dog wagging to the left, their heart rates increased and they appeared anxious. When they saw another dog wagging to the right, they remained relaxed.
The findings show that dogs, like humans, have asymmetrically organized brains in which the left and right sides play different roles, the researchers said.
"The direction of tail wagging does in fact matter, and it matters in a way that matches [brain] hemispheric activation," Giorgio Vallortigara, of the Center for Mind/Brain Sciences of the University of Trento, in Italy, said.
Vallortigara said it's not likely that dogs intend to communicate those emotions to other dogs. It's more likely that the differences in tail wagging direction are simply the result of activity in different sides of the brain.
He also said that a dog's ability to recognize and respond to tail wagging direction may be useful to veterinarians and dog owners.
"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," Vallortigara said.
The Animal Behavior Clinic at Tufts University has more about animal behavior.