This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American
I’m right handed. Utensils, pens, pencils, and of course my toothbrush are all operated by my right hand. Like roughly 90% of people, my left hand simply isn’t cut out for much on its own.
Dogs, outfitted with paws not hands, also appear to prefer one paw over the other. In dogs, paw laterality — or paw preference — is explored not with forks or pencils, but with more dog-appropriate motor tasks. Studies have asked which paw dogs use to reach toward food or which paw they use to remove something from their body, like a blanket. Researchers have even checked which paw dogs first lift to walk down a step and which paw they “give” when asked to “give” paw. To date, it has been assumed that, like us, dogs have a “hand” preference.
But Deborah Wells, a longtime laterality researcher, wondered if something was missing. Studies of paw preference typically use only one test to investigate paw preference. As a result, it is unclear whether “dogs harbour consistent paw preferences” or, on the other hand (ha!), whether paw preference instead might be task-specific. Maybe a dog consistently reaches for food with the right paw, but is more likely to lift the left front paw to walk down a step.
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Wells and colleagues at the Animal Behaviour Center, Queen’s University, Belfast, took the natural next step (ha again!). They tested 32 pet dogs on four different paw preference tests to see whether dog paw preference was consistent across tests. To check preferences over time, a subset was tested 6 months later. This research was recently published in Behavioural Processes.
All dogs participated in four tests: The Kong Ball Test assessed which paw dogs used to stabilize a Kong that had food in it; the Tape Test assessed which paw dogs used to try and remove a small piece of scotch tape stuck to their nose; the Lift Paw Test assessed which paw dogs lifted to “give” a paw; and the First-Step Test assessed which paw dogs first lifted when walking down a step. For each test, multiple instances of paw use were recorded to explore preference strength and direction.
Wells had been on the right track. Instead of dogs showing consistent paw preference — always using the left or right paw in each test — paw preference was instead task-specific. A dog might use the right paw in the Kong test but lift the left to take a step. The findings, the researchers suggest, “do not therefore support the interpretation of true ‘pawedness’ in the dog.” At the same time, test-specific paw preferences seemed stable over time, apart from the Tape Test, which the researchers do not recommend for future laterality studies (dogs were more “frantic” in their movements to remove the tape and more likely to use both paws).
If the purpose of motor-bias research is not yet clear, I assure you laterality researchers are not trying to organize a well-attended round of hokey pokey. Instead, researchers are interested in motor bias because the relationship between motor bias and brain lateralization can have animal welfare implications. For example, animals showing left-limb preference tend to be more active in the right hemisphere of the brain, and these individuals “show stronger fear responses than right-limbed animals, which tend to be left-hemisphere dominant.” An earlier study by Wells and colleagues found that left-pawed dogs were more “negative or ‘pessimistic’ in their cognitive outlook than right-pawed or ambilateral individuals.” But the current study might put a damper on efforts to connect paw preference with broader animal welfare implications. If paw preference in dogs is not consistent between tasks, the researchers explain, “the study raises questions as to which test of paw preference is the most appropriate to employ.”
Reference
Wells, D. L., Hepper, P. G., Milligan, A. D. S., & Barnard, S. (2018). Stability of motor bias in the domestic dog, Canis familiaris. Behavioural Processes, 149, 1—7.