Studies & Research
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On any given day, I am apt to observe my dogs. For hours, I may just be with them, watching. They delight me with their humor and they surprise me with their varied language. A few years ago, curiosity started me on a wonderful exploration into the canine vocabulary, and in the end, I created quite a stir with my research into the vocalizations dogs produce while playing. This line of inquiry began one afternoon while I was watching Goodall, my Briard puppy,who was about six months old at the time. Goodall is a whimsical dog, and on this particular afternoon, he was lying lazily on his side, spinning a swivel chair around and around. He would strike the chair with his front paws to start it spinning, and then he would use his hind paws to keep it going—a synchronized pattern of pawing and laughing.
That’s right, I said laughing. Until recently, it would have been career suicide to attribute this ability to anything but a human animal. But here was my little puppy, tossing his head back and producing a huh-huh-huh sound. The amount of air he forced out of his mouth was considerable, yet he was not exerting much energy while spinning the chair, so he wasn’t panting. I thought the sound may have meaning, and wanted to find out what that meaning was.
I asked other ethologists and animal behaviorists if they knew anything about dog laughter. Finally, at a conference in Chicago—“Animal Social Complexity and Intelligence,” 2000—Jane Goodall (after whom my dog is named) and Marc Bekoff (a scientist who has studied play in canids for over 30 years) suggested that I conduct the research and answer my own question. I took their advice, and what I found delighted me: Dogs produce all sorts of sounds during play. They growl, whine, bark and emit a forced, breathy exhalation through the mouth, a doglaugh, if you will.
Dogs also play-bow, paw, box and exhibit a relaxed mouth known as a play-face, or smile.When a dog smiles, the sides of the mouth are pulled far back and the lower jaw is slightly (or widely) open. The upper teeth do not show, but the lower teeth may be visible.When you see a dog smiling, it is an unmistakable expression.
Before my playback experiment to determine if the “forced breathy exhalation through the mouth” (the dog-laugh) had a discrete meaning, I examined the sound using spectrograph analysis. The sound of the dog laugh, which spiked to 44k cycles, looked very different than that of the pant, which is flat (see graphs at right, or go to laughing-dog.org to hear for yourself). These differences encouraged me to take the next step in the research, playing the sound to dogs and logging their responses.
Individually tested dogs responded to the dog-laugh by picking up toys and playbowing to the computer, the experimenter or the neutral dog. These responses contrasted to their reactions to recordings of growls, whines and barks; puppies piddled when they heard the growl, even though it had been recorded during play, while adults moved away from the growl and stood by the door. It appeared that the forced breathy exhalation meant a laugh and good times ahead!
This discovery was rewarding, but the other dog secrets revealed by my research were even better (to me at least).
Secret Number One: Dogs Are Fair-Minded
While exploring the language of dogs, I also investigated rules and role reversal during dog play. Dogs appear to be very fair-minded creatures. They have rules, but the rules are flexible. For example, while dogs are playing, they have a notion of a safe place to stop and rest. This rule is very similar to children having a “safe base”during tag and hide-and-seek games. During dog chase games, the chasee usually has an object of some sort—a stick or ball—to designate his role, and all other dogs chase the dog with the object.However, when the chasee becomes tired or thirsty, he can run to the water (or wherever the dogs have designated as “safe”), put the stick down and drink. All the other chasers stop (and sometimes drink as well) and wait for the chasee to pick up the toy and begin running again. This rule is flexible, because when young (or older) dogs, who tire more quickly than adolescent dogs, cannot make it to the water, they run to the closest pair of human legs and stop and stand in between them. All the chasers also stop and wait. Then, the game continues.
Dog chase and tag games are engaging —the whirling and dashing are as balanced as a sophisticated ballet sequence, and timing is everything. (Of course, as with any spectacle, we secretly wait for the slapstick moment—a miscalculated leap, for example.)
Secret Number Two: Dogs Have a Sense of Other (Role Reversal)
Dogs understand roles, and reversing roles. For example, dogs can be both the chasee and the chaser, depending on who has the object; sometimes, during tag, no object is necessary. The role reverses with a playful glance over the shoulder. For many researchers, it has been a challenge to find a way by which to investigate selfconsciousness. But I believe the answer to this dilemma is to investigate an animal’s sense of “other,”which is required in order to have a sense of “self.”*
Dogs exhibit this sense of other during play. They understand roles and how they change. For example, dogs switch from chaser to chasee without skipping a step. The chaser will sweep around to the side of the chasee, then move ahead while looking back over his shoulder. With a single glance, the chaser becomes the chasee.
Secret Number Three: A Laughing Dog Calms an Anxious Dog
Earlier, I noted that my research raised a ruckus.When I presented my findings on the meaning of the breathy exhalation, Dr. Janice Willard, a behavioral veterinarian, challenged me to apply the results to something that could help dogs. In 2005, I did just that by designing an experiment that would determine whether or not playing the dog-laughter recording would ameliorate stress-related behavior in shelter dogs.Not only was it successful in doing that, it appeared to have a calming effect on the dogs as well. The dogs exhibited significantly fewer stress-related behaviors such as barking, lunging, cagebiting, tail-chasing and cowering, and a significant increase in pro-social behaviors, including quietly sitting or lying at the front of the kennel.
Initially, I was surprised by this calming effect, because laughter seems to me to be so rousing. However, after reading Jaak Panksepp’s work (Burgdorf, J. & Panksepp, 44 Bark Sept/Oct 2007 J. .Tickling induces reward in adolescent rats, Physiology & Behavior, 72, 167–173), I had a better understanding of the way the dog-laugh could calm. According to Panksepp, during laughter the pleasure center of the brain is activated. Perhaps listening to the sounds of others laughing really does have a healing effect —perhaps listening to other dogs laughing calms our anxious dogs.
While these three secrets by no means constitute a complete list, they illustrate a direction of inquiry into our dogs’ lives. We as dog guardians may have suspected these secrets to be true, but science is finally supporting our affectionate observations. According to recent DNA research by Leonard, Wayne, Wheeler et al., domestic dogs have been sharing the company of humans for thousands of years. During this lengthy common history, dogs and humans have developed mutual communication signals—gaze, touch, smiling and laughter. May we continue our lasting relationship for another 100,000 years, and may our communications continue to deepen.
*Studies have been done on this topic, most recently in 2006, when an Emory University graduate student using Asian elephants as subjects replicated earlier studies and found that his three subjects did indeed recognize themselves in a mirror. (Plotnik, Joshua M., de Waal, Frans B. M., & Reiss, Diana.  Self-recognition in an Asian elephant. Published online Oct. 30, 2006; PNAS doi:10.1073/pnas.0608062103.)
Image: Sergio Ruzzier