The Sociable Dog: A Systematic Experimental Investigation of Canine Social Behaviors
Brown, Kelsea Marie
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A growing number of studies make claims about canine sociability in both applied and basic contexts. Despite the prevalence of sociability assessments, it remains unclear what exactly these tests can tell us about a dog and how they do or do not relate to other concepts such as social cognition, behavior synchronicity, and learning. Additionally, multiple types of tests exist, with procedural variations within and between tests; there is currently no standard for measuring sociability in dogs. The purpose of these six experiments was to systematically investigate the concept of canine sociability. First, we examined whether procedural differences among canine sociability tests would affect dogs’ behavior. In Experiment 1, we used a mixed-subjects design to assess whether experimenter posture (standing, sitting, or kneeling) and presence of attention (petting and praise or none) affected leashed dogs’ social behavior. Mixed-effect logistic regression modeling showed statistically significant main effects and interactions between posture and social contact. On average, dogs were more social when the experimenter knelt and provided social contact. However, there were individual differences in how dogs were affected by changes in procedure. In Experiment 2, we examined correspondence between leashed and unleashed dogs’ social behaviors including latency to approach, time in proximity, following patterns, eye gaze, body orientation, jumping, and touching. Individual differences were examined by calculating a binomial mixed-effect logistic regression with condition (leashed, off-leash, following) and subject ID as fixed effects. Interactions were statistically significant for all behaviors, indicating that individual differences were present. The results have implications for the validity of sociability tests. In two follow-up experiments, correspondence between seven assessments was evaluated: Sociability (open field), Synchronicity, Reinforcer Efficacy, Pointing, Landmark, Separation, and Reunion. Forty-four dogs from a municipal animal shelter served as subjects. Distinct paradigms were observed, with high correlation of behaviors within tests, and little or no correlation of behaviors between test types. The data have implications for the validity of sociability assessments and the ways in which we discuss canine social behaviors, social cognition, and attachment. Our fifth experiment delved deeper into the mechanisms that drive dogs’ abilities to follow human pointing gestures. Though the two-choice task has been used for decades, researchers still disagree on the mechanism that drives this skill. One hypothesis suggests that dogs’ sociable nature—selected for during domestication—allows them to better communicate with humans, including understanding human communicative gestures. The opposing hypothesis is that dogs, within their lifetime, have learned to follow pointing gestures by simply interacting with humans. To tease apart the underlying mechanism (sociability or learning propensity) of point following behavior, we measured dogs (n = 24) on a sociability assessment, then subjected them to three different two-choice tasks: pointing, novel landmark (difficult learning test), and familiar landmark (easy learning test). There was little to no correlation between pointing and the landmark controls, and pointing was weakly negatively correlated with sociability. Moreover, when dogs were divided into high-sociability and low-sociability groups, no statistical differences were found for performance on any of the assessments, including pointing. We consider that three distinct constructs were measured: sociability, learning propensity, and social cognition. In the final phase of our study, we investigated the heritability of canine sociability. To date, the heritability of sociable behaviors has not been widely studied. A unique population of dogs—retired racing greyhounds—may prove to be an astounding population with which to study heritability. Because the population is large and dogs’ lineages are meticulously traced back to the 1800s, and because racing procedures dictate a controlled rearing environment, heritability estimates can be determined for any conceivable phenotype. In this first-ever study of its kind, we mapped pedigrees for over 200 dogs and calculated relationships between genetic relatedness and owner-reported sociability behaviors as measured with C-BARQ. We calculated animals’ individual inbreeding coefficients as well as additive genetic relationship coefficients between all subjects in our sample. A statistically significant regression equation was found for predicting sociability based on inbreeding coefficient (F(1, 205) = 4.25, p < .05) with an R2 of .02. Between dogs, additive genetic relationship was a statistically significant predictor of similarity in human sociability, but not for dog friendliness. Results indicated that there is an element of heritability involved in social behaviors, but overall very little variation is explained (R2 ranged from .002 – 00001). This highlights a perhaps even more interesting finding that, when genetics are accounted for and environmental upbringing is controlled, there is still a great deal of behavior variation within our homogenous sample of dogs.