Appeasement signals used by dogs during dog–human communication

Abstract

Abstract The aim of this study was to examine the occurrence of the appeasement signals away and of shown by healthy dogs toward strangers in a standardized behavioral test. The 116 participating dogs were aged at least 13 months and could be any breed. Dogs were guided by their owners through the behavioral test which included a variety of test situations. The people conducting the test were previously unknown to the dogs and behaved in a neutral, friendly, or threatening way depending on the test situation. This design allowed us to investigate interspecific communication with a focus on the chosen appeasement signals in different contexts. The expressive behavior of the tested dogs was evaluated based on video. We found that both signals, licking of lips and looking away, may serve as appeasement signals in dog–human communication. These signals were directed more often toward those conducting the test by dogs in threatening and conflict-ridden test situations. However, our results also show that the dogs responded with significantly fewer appeasement signals in the face of a major threat than in less threatening situations. A possible explanation may be that in the case of a major threat, these appeasement signals are no longer expedient, and the dogs select more promising behavioral strategies, such as clearly behavior or escape. Furthermore, we found that licking of lips was a common component of the greeting behavior of dogs toward humans. This signal was observed significantly more often during active submission (i.e., friendly approach with submissive signals) than during sociopositive approaches. For this reason, lip licking may play the same role as in the intraspecific communication: as appeasement signal occurring with reduced interindividual distance and sent in advance to express peaceful intentions.