When a dog rolls onto its back during play, does the maneuver indicate submission, akin to a person crying “uncle,” or does it signify something else altogether? A study published earlier this year, by Kerri Norman and her colleagues at the University of Lethbridge in Alberta and at the University of South Africa, comes down on the side of “something else.”
Their report appeared in January in an issue of Behavioural Processes devoted to canine behavior. Investigating what behaviors mean during dog-dog play is not new. For example, you have probably heard of play signals that help dogs to clarify play from not play. These signals indicate something like, “Hey, when I just bit you in the face, I didn't mean it like ‘I'M BITING YOU IN THE FACE.’ It was just for fun. See! Here's a play bow for additional clarity. All fun here!” Play signals may also include exaggerated, bouncy movements or presentation of a “play face”; they start or maintain play, and they occur around potentially ambiguous behaviors—such as a bite, tackle or mount—or anything that might be misconstrued as not playing. But not all behaviors that appear during play between dogs are as well studied.
Outside of play, rolling onto one's back is often seen as a submissive gesture that curtails or avoids aggression by another dog. In a classic 1967 paper in American Zoologist, Rudolf Schenkel of the University of Basel in Switzerland describes this so-called passive submission as expressing “some kind of timidity and helplessness,” like coming out with your hands up or waving a white flag.
Some have suggested that the rollover performed in dog-dog play is still about preventing aggression. Owners observing playing dogs from the sidelines often take this a step further—the dog spending more time on its back is labeled “submissive” or “subordinate,” whereas the dog on the top is “dominant.”
But what if rolling over means something different during play? Norman and her colleagues wanted to know whether “rolling over onto the back and adopting a supine position” during play is an “act of submission” and serves to stop the interaction or hinder subsequent aggression. Or, they speculated, it might be essentially playful, “executed tactically, for combat purposes,” to encourage play, avoid a play bite (defensive maneuver) or deliver a play bite (offensive maneuver).
They collected data in two different contexts: staged play sessions where a medium-sized female dog was paired with 33 new play partners of various breeds and sizes, and 20 YouTube videos where two dogs played together—half the videos paired similarly sized dogs, and the other half had dogs of different relative sizes.
Not all observed dogs rolled over during play, particularly in the staged play sessions, where only nine partners rolled over when playing. In the YouTube videos, 27 of the 40 dogs rolled over, and it occurred in both similarly sized and differently sized pairs. If your dog is not a roller during play, you are in good company.
For dogs that did roll over, what did it mean? The researchers examined all instances of the behavior to see whether they were associated with submission—decreasing play, remaining passive, or being performed by the “smaller or weaker” partner—or were instead associated with the interactive, fun, combative nature of play, where rollovers preceded “launching an attack (offensive), evading a nape bite (defensive), rolling in front of a potential partner (solicitation) or rolling over in a nonsocial context (other).”
The findings are stark: the smaller of the two play partners was not more likely to roll over than the larger dog. Additionally, “most rollovers were defensive and none of the 248 rollovers was submissive.” Most of in-play rollovers in the study, the researchers found, were part of play fighting (meaning the fighting was itself playful, not real fighting).
But could it be that once dogs are on their back, submission kicks in? For example, a dog could go on its back to avoid a neck bite and then lie motionless, suggestive of passive submission. But that is not what the dogs did. Instead once on their back, dogs in the supine position both blocked playful bites and launched them at their partner.
Another way to think about rolling over in play is as a self-handicapping behavior that helps dogs of different sizes or sociabilities play together. Self-handicapping is instrumental to play, and it implies that a dog is tempering its behavior. For example, during play, dogs do not deliver bites at full force, and a larger dog might roll over to allow a smaller dog to jump on or mouth it. Some dogs will even use this behavior to invite bites and solicit play from another dog.
It is not safe, then, to assume that a dog sliding onto its back during play is essentially saying, “YOU CAME ON TOO STRONG” or “OKAY, YOU WON THIS ROUND!” In some contexts, this posture is certainly associated with fear or with defusing or preventing aggression, but the recent study reminds us that rolling over, as with many behaviors, does not have a single, universal meaning. Instead it is often just playful.