One of the first things a person learns about dogs is that they wag their tails when they are happy. While this is true, it turns out that the tail motion conveys a lot more information. An article on NPR.com describes a recent study that explored how specific kinds of tail wagging are interpreted by other dogs.
According to the results of the research performed by Giorgio Vallortigara of the University of Trento in Italy and his colleagues, the wagging motion is not symmetrical: in fact, dogs wag predominantly to the right or to the left. The direction makes all the difference:
“The question was at this point, ‘Does asymmetric tail wagging convey meaning to other dogs?’ ” says Vallortigara.
To find out, they had 43 dogs wear some little vests that would monitor their heart rates. Then they had the dogs watch some special images of dogs that were designed to remove all stimuli except the wagging tail.
The results are fascinating and suggest that dogs are attuned to “asymmetries” and can use that information to gauge how an interaction is going to go.