What type of body language is most likely to be misinterpreted by people?

I think it’s likely dogs wagging their tails. The number of parents I’ve overheard telling children a dog is friendly because their tail is wagging, and the number of people walking past an anxious dog and commenting how happy they are because their tail is wagging, is unfortunately, and likely dangerously in some situations, high.

While I don’t know the origins of the tail wagging = a happy dog rhetoric, it is definitely commonly referred to in many cultures. Those of us working in behaviour and training are well aware that isn’t always the case. However, there’s some pretty interesting research that has been done on tail wagging, so let’s dig into the science.

Scott & Fuller’s classic book, Genetics and the Social Behavior of the Dog that was published in 1965, described tail wagging as a  ‘pleasurable emotion toward a social object’. They described a pattern of rapid, horizontal tail wagging whose only function is a social one, and similar to a human smile. While this may be the case in young puppies, our current interpretation and knowledge of tail wagging in dogs goes beyond it being simply a positive social signal.

Tail wagging beliefs

The general public’s knowledge about dog body language and behavior may be improving, however there was a study published in 2016 that showed adults are misinterpreting tail wagging in dogs (Salgirli Demirbas et al., 2016). The study asked both adult dog owners and non-owners to interpret video interactions of dogs and children. An expert panel also observed the videos and determined that the videos all contained interactions where they classified the dogs as having emotional conflict, lacking confidence, and fearful or anxious. A majority of the participants misclassified the fear or anxiety as relaxed and confident, and all participants in the study indicated that tail wagging was a behavioral cue for positive emotion.

Tail wagging development

Scott and Fuller also followed the development of five breeds of dogs, and looked specifically at the development of tail wagging. They found that tail wagging first appeared at 17 days of age in Cocker Spaniels and Shelties, and the last breed to be observed beginning to wag their tails were Basenjis at 88 days of age. By 30 days of age, half of the dogs were observed wagging, so this is a behavior that develops early in the socialization period of the dog.

Tail position and wagging

In general, when looking at tail motion, we look at both the position of the tail and its’ movement. In a review paper by David Mellor (2018) that was looking at tail docking, he summarized characteristic forms of tail wagging as well as the presumed emotional states associated with them. These are listed below, and show the wide range of communication that tails may exhibit.

(Mellor, 2018)

Tail wagging communication

A study looked at the responses of dogs to different tail lengths and whether a tail was wagging or still (Leaver & Reimchen, 2008). A model dog was used that resembled a lab, and the researchers adjusted whether the dog had a ‘normal’ length tail or a shortened one, both of which could be moving (meant to replicate a loosely wagging tail) or still.

The researchers then looked to see how dogs approached the robotic dog. Smaller dogs were less likely to approach on the whole, but larger dogs were more likely to approach the robotic dog with a long tail if it was wagging compared to the long tail being still. When the tail of the robotic dog was short, then larger dogs were just as likely to approach if the tail was wagging or still.

The researchers concluded that communication between dogs from tails is more effective if the tail is long. This also has implications for dogs that we bred or have cosmetic procedures performed such as docking, which is very likely taking away an important method of canine communication.

Tail wagging asymmetry

We now know that dogs have asymmetric tail wags, meaning that they may wag more to the left or more to the right in different circumstances.

A study looking at 30 pet dogs (Quaranta et al., 2007) found differences in which side the tail was wagging based on what they were observing.

Dogs were placed inside a large wooden box and were shown different stimuli: their owner, a stranger, what they termed as a dominant dog which was an unfamiliar male Malinois, and a cat. Videorecordings were made of each dogs’ tail when they viewed these stimuli. Tail wagging scores were derived from videorecordings, where observers looked at the amplitude of the wagging. They found a right-sided bias to wagging with people and with the cat, with familiar owners having the largest amplitude, human strangers a lesser amplitude, and reduced tail movements, although still biased to the right side, with cats.

With the strange dog, however, tail wagging was biased towards the left side.

Not only do we see a difference in tail wagging asymmetry when dogs see different things, but it seems it may also be important in communication between dogs (Siniscalchi et al., 2013). In this study dogs were shown video images of a dog that had no wagging, left-asymmetric wagging, or right-asymmetric wagging. When dogs observed the left-biased wagging, they had higher heart rates. Dogs were also videotaped and their behavior was scored as ‘relaxed/neutral’, ‘stress/anxiety’, or ‘alerting/targeting’. When observing a right-biased wag, dogs were more likely to be scored as ‘relaxed/neutral’, while those observing left-biased wags were significantly more likely to be scored as ‘stress/anxiety’ or ‘alerting/targeting’. Dogs observing left-biased wagging showed a greater emotional reaction than those observing right-biased wagging.

If you’d like a less technical version of this to share with clients, one can be found on the Landmark Behaviour Blog that is written for pet owners.


Scott J.P., Fuller J.L. 1965. Genetics and the social behavior of the dog. Chicago: University of Chicago Press
Leaver, S.D.A., & T.E. Reimchen. 2008. Behavioural responses of Canis familiaris to different tail lengths of a remotely-controlled life-size dog replica. Behaviour. 145:377-390.
Mellor, D.J. 2018. Tail docking of canine puppies: reassessment of the tail’s role in communication, the acute pain caused by docking and interpretation of behavioural responses. Animals. 8:82.
Quaranta, A., M. Sinischalchi, F. Vallortigaraz. 2007. Asymmetric tail-wagging responses by dogs to different emotive stimuli. Current Biology. 17:R199-R201.
Siniscalchi, M., R. Lusito, G. Vallortigara, A. Quaranta. 2013. Seeing left- or right-asymmetric tail wagging produces different emotional responses in dogs. Current Biology. 23:2279-2282.