Limb asymmetry assessment: Aligning human and dog approaches to laterality

Laterality biases are widespread across animal species, and motor asymmetry remains the most extensively explored manifestation of these behavioural biases. It refers to the individual's bias for relying more heavily on one half of the body for everyday actions, most prominently expressed in humans in the preferential use of one hand over the other (i.e., handedness). Despite its importance, there is currently little common methodological ground for assessing motor laterality across species, a gap that limits comparative studies. We briefly review the history of handedness assessment tools in humans, highlighting strengths and limitations of different approaches (self-report questionnaires, performance assessment and preference tests). We then describe the state-of-the-art in the measurement of lateral preference in motor tasks in a species with a close relationship with humans, namely the domestic dog (Canis familiaris). Evolutionarily, dogs and humans have been exposed to common ecological and social pressures that could have shaped their behavioural organization, and a laterality preference has been shown also in dogs. Nevertheless, research on human and dog motor laterality has mostly been conducted independently from each other, making cross-species research difficult. We discuss how methodological approaches used in humans can inform research in dogs, supporting more comparable research.