The humorist, Robert Benchley, once observed "A dog teaches a boy fidelity, perseverance, and to turn around three times before lying down."
I suppose that this quote sprang into my mind this morning was when I received a phone call from a reporter who wanted to know why it is that dogs often turn in circles before lying down. This is such a commonly observed behavior in dogs that we should have expected that there would be a reasonable amount of scientific literature which explains this behavior. Unfortunately my search of published research revealed no studies that specifically address this spinning behavior in dogs (other than those cases where excessive and prolonged circling shows up as a symptom of obsessive-compulsive disorder in a small number of dogs).
It appears that the absence of actual data doesn't stop people from speculating about why this turning behavior appears. Some people have suggested that it is an evolutionary holdover, where the dog is doing this for security. In essence the dog is checking out the surrounding area to make sure there are no threats before settling down.
Another argument is that this circling behavior is done to chase away any possible vermin that might be hanging around, or perhaps to uncover any random stones or prickly twigs that might make this sleeping area less comfortable.
Perhaps the most sensible suggestion is that dogs are, in effect, creating a little nest for themselves by trampling down grass or brush in the area before they settle in for a nap.
Speculation in the absence of data has always bothered me, probably because of my training as a scientist, so I decided to collect some data on the issue. Specifically I wanted to test the idea that the dogs were turning around in circles to flatten out the area where they wanted to rest and essentially build themselves a little nest.
The experimental setup was really very simple. The notion was that if the dogs were circling to make an uneven surface more comfortable, then they should be less motivated to do this if the surface had no lumps or bumps. To test this idea we set up a wire rectangular exercise pen (approximately 3 feet by 6 feet in size) and placed it in a corner of a large open room. The floor of the exercise pen could either be covered by a flat densely woven piece of carpet fabric (which presumably would need no additional trampling down) or by a piece of loosely woven shag carpet which was placed into the pen with no attempt at smoothing out lumps or wrinkles, (which should mimic an uneven surface out in the wild).
A total of 62 pet dogs were tested (31 for each of the surfaces). The dog's owners simply placed their dog in the exercise pen, and turned and walked away to the far side of the room where they sat down and read a magazine or drank coffee for up to 15 minutes. The experimenter who was seated on a chair next to the owner observed the dogs and noted their behavior when they decided to lay down. Whether the dog turned a full circle before lying down was noted, and those instances where more than one rotation occurred were also noted.
The results were rather straightforward. On the smooth surface, roughly one out of every five dogs (19%) turned at least one full circle before laying down. On the shag carpeted, uneven surface, more than half of the dogs (55%) turned at least one full circle before they finally rested. That means to say that the dogs were nearly 3 times more likely to circle before laying down on the uneven surface than on the smooth surface. That is a large difference which is statistically significant*. Furthermore, if we look at the number of dogs who circled more than once before laying down, we find only one who did so on the smooth surface, as compared to 19% of the dogs who circled more than one full rotation before they went down on the uneven surface. Although no specific count was kept, several dogs on the uneven shag carpet also poked or dug at the surface before circling, and this behavior was never observed for the dogs on the smooth surface.
Thus it appears that when dogs are presented with a soft, uneven surface, they are more likely to turn in circles before they lie down. Obviously this particular set of data cannot say that that is the only reason that dogs turn in circles before resting, but it does indicate that one reason that dogs are spinning about is to make themselves a more comfortable temporary "nest" to nap in.
Stanley Coren is the author of many books including: The Wisdom of Dogs; Do Dogs Dream? Born to Bark; The Modern Dog; Why Do Dogs Have Wet Noses? The Pawprints of History; How Dogs Think; How To Speak Dog; Why We Love the Dogs We Do; What Do Dogs Know? The Intelligence of Dogs; Why Does My Dog Act That Way? Understanding Dogs for Dummies; Sleep Thieves; The Left-hander Syndrome
Copyright SC Psychological Enterprises Ltd. May not be reprinted or reposted without permission
* z=2.89, p <0.01