I’ve got the ‘dog play’ bug, arguably one of the better winter bugs to have. I recently covered which toys dogs prefer (the answer: new ones, although old ones can be reinvigorated), as well as the unfortunate finding that when a dog’s not “playing right,” it could be you, not them. But toys and people are only part of play. I haven’t said anything yet about the huge topic of dog-dog play!

Fear not! Enter a new study on dog-dog play published just this month in Behavioural Processes as part of an open access Special Canine Behavior Issue. The study focuses on a particular behavior that you’ve probably seen countless times — rolling onto the back during play. The scientists came to a somewhat counter-intuitive conclusion, and if you’re like the people I hear chatting at the dog park, you might not be spot on about what it means.

Before we get to the new study, investigating what behaviors mean during dog-dog play is not new. For example, you’ve probably heard of play signals that help clarify play from not play. Play signals help say 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 — like exaggerated, bouncy movements, or presenting a “play face” — start or maintain play, and they occur around potentially ambiguous behaviors — like a bite, tackle, or mount — or anything that might be misconstrued as ‘not playing.’ Play signals reinforce, “Woohoo! We’re not fighting! We’re playing!”

But not all behaviors that appear during dog-dog play are as well studied. Here to demonstrate today’s play behavior of interest is Theodore, or Teo for short. Prior to bringing his play skills to an international audience (he has his own Facebook page, Pibbling with Theodore), Teo was one of 367 dogs rescued from the second largest, multi-state dog fighting bust back in 2013. He currently lives a very different life alongside his four-legged siblings and Trish McMillan Loehr, MSc, CDBC, CPDT-KA, of Loehr Animal Behavior in Weaverville, North Carolina. Teo enjoys playing, making art with household items, and recycling.

Without further ado, Theodore in a video of slow-motion play with his “sister,” Lili (and Lili is making the slow-mo dinosaur noises).

Theodore shows many excellent play behaviors, but it's ‘rolling onto the back’ that’s the focus of a new study by Kerri Norman and colleagues at the University of Lethbridge and University of South Africa. Their question is something you may have wondered yourself: when a dog rolls onto his or her back during play, what does it mean? Is it an indication of submission akin to a person tapping out or screaming “Uncle,” or is it instead "a combat maneuver adopted as part of an ongoing play sequence"?

Rolling onto one’s back is classically seen as a submissive gesture that “curtails active aggression.” Passive submission describes an individual voluntarily or "spontaneously [rolling] onto its back." In a classic 1967 paper in American Zoologist, Rudolf Schenkel describes passive submission as “[expressing] some kind of timidity and helplessness." Like coming out with your hands up or waving a white flag, passive submission is thought to prevent aggression.

Some have suggested that the rollover is still about ‘preventing aggression’ even when performed during dog-dog play. 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’ while the dog on the top is ‘dominant.’ These labels often fit with a person's worldview about dogs and asymmetries in relationships.

What if rolling over means something different when it's during play? Norman and colleagues set out to investigate the meaning and function of rollovers during play. They wanted to know whether “rolling over onto the back and adopting a supine position” is an “act of submission” and serves to hinder subsequent aggression, or is instead, “executed tactically, for combat purposes” to solicit play, avoid a play bite (defensive maneuver), or deliver a play bite (offensive maneuver).

The researchers collected data on dog-dog play 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 — with half the videos including similarly sized dogs and the other half including dogs of different relative sizes.

Why the roll?

First, not all dogs rolled over during play. This was particularly notable in the staged play sessions, where only 9 partners rolled over during play. In the YouTube videos, 27 of the 40 dogs rolled over, and rolling over occurred in both similarly-sized and differently-sized pairs. If your dog isn’t a roller during play, you’re in good company.

For dogs who did roll over, what did it mean? The researchers examined all instances of rolling over 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, combative nature of play, where roll overs preceded “launching an attack (offensive), evading a nape bite (defensive), rolling in front of a potential partner (solicitation) or rolling over in a non-social context (other).”

The findings are stark: the smaller of the two play partners was not more likely to rollover than the larger dog. Additionally, “most rollovers were defensive and none of the 248 rollovers was submissive.” Here is a figure for you visualizers out there:

But once on their backs, maybe this is where submission kicks in? For example, a dog could go on his back to avoid a neck bite and then lay motionless, suggestive of passive submission. But that's not what the dogs did. The researchers report, “no dog rolled over in response to an approach or aggressive action by the partner and did not remain passive in its back.” Instead, like you saw in the video of Theodore, the Playing Wonderdog, once on their backs, dogs in the supine position both blocked and launched bites at their partner.

What does this mean?

Wondering about why dogs do what they do seems to be an international pastime. But assuming that a dog rolling onto his back during play is akin to saying, you “came on too strong” or, ”OK, you won this round!" seems like a mistranslation. In some contexts, rolling onto the back is certainly associated with fear, or defusing or preventing aggression, but this new study reminds that ‘rolling over,’ like many behaviors, does not have a single, universal meaning. Instead, rolling over during play is often just playful. I think Theodore would agree.

1.13.2015, 9:00 PM Updates

I am happy that so many people are discussing this study! Here are a few more important points about rolling over and dog play:

1) When two dogs are playing, rollovers most often facilitate play. For example, a dog on its back often engages in playful sparring with another dog, delivering or avoiding neck bites, or engaging in open-mouth lunges. The researchers in the above study found that the majority of in-play rollovers were part of play fighting (meaning the 'fighting' was itself playful, not real fighting). The important takeaway is that rolling over during play is about play, it is NOT about ‘aggression’ as this Daily Mail headline incorrectly states.

2) Another way to think about rolling over in play is as a self-handicapping behavior because it helps dogs of different sizes or sociabilities play together. Self-handicapping is instrumental to play, and it implies that a dog is tempering his or her behavior in some way. 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 him. In Inside of a Dog: What Dogs See, Smell, and Know , Alexandra Horowitz describes the behavior: “Some of the largest dogs regularly flop themselves on the ground, revealing their bellies for their smaller playmates to maul for a while—what I called a self-takedown.” The researchers in the above study note that “some of the present data indicate that the bigger dog is more likely to [rollover].” Self-takedowns can be a type of self-handicapping behavior that promote play.

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References

Horowitz A. (2008). Attention to attention in domestic dog (Canis familiaris) dyadic play, Animal Cognition, 12 (1) 107-118. DOI: http://dx.doi.org/10.1007/s10071-008-0175-y

Norman K., Pellis, S., Barrett, L., & Henzi, S. P. (2015). Down but not out: Supine postures as facilitators of play in domestic dogs, Behavioural Processes, 110 88-95. DOI: http://dx.doi.org/10.1016/j.beproc.2014.09.001 (OPEN ACCESS HERE)

Schenkel, R. (1967). Submission: Its Features and Function in the Wolf and Dog, American Zoologist, 7 (2) 319-329. DOI: http://dx.doi.org/10.1093/icb/7.2.319