Do dogs respond to play signals given by humans?

Play signals are known to function in the solicitation and maintenance of intraspecific play, but their role in interspecific play is relatively unstudied. We carried out two studies to examine interspecific signalling when humans play with domestic dogs, Canis familiaris. In the first, we recorded dog–owner play sessions on video to identify actions used by 21 dog owners to initiate play with their dogs. Thirty-five actions were each used by three or more owners. These included postures, vocalizations and physical contact with the dog. The actions varied greatly in their apparent success at instigating play which was, surprisingly, unrelated to the frequency with which they were used. We then did an experiment to determine the effect of composites of commonly used signals upon the behaviour of 20 Labrador retrievers. The performance of both ‘Bow’ and ‘Lunge’ by a human altered the subsequent behaviour of the dogs. Both signals caused increases in play, and Lunge produced significant increases in play bout frequency and mean bout duration. The efficiency of both these postural signals was enhanced when they were accompanied by play vocalizations. Thus, specific actions used by humans do communicate a playful context to dogs and can be described as interspecific play signals