Appeasement function of displacement behaviours? Dogs’ behavioural displays exhibited towards threatening and neutral humans

Abstract

Appeasement signals are behavioural patterns displaying an animal’s non-aggressive attitude and are hypothesized to reduce the aggressive behaviours in the receiver. In domestic dogs, specific displacement behaviours (i.e., behavioural patterns exhibited without an apparent function related to the ongoing situation), have been suggested to function as appeasement signals. To test this possibility, we assessed whether the occurrence of these behaviours was dependent on a social conflict context, predicting that, if displacement behaviours also function as appeasement signals, they should be more prevalent in a conflict vs. non-conflict context. Fifty-three dogs were exposed to two unfamiliar humans approaching them in either a mildly threatening or neutral way. We categorized the attitude of the dogs towards the strangers as “reactive”, i.e., barking and lunging towards the stimulus, and “non-reactive”, i.e., remaining passive in front of the stimuli. We coded dogs’ displacement activities and modelled their duration or frequency as a function of the interaction between the test condition and the attitude of the dog. Displacement behaviours of “blinking”, “nose licking” and “lip wiping” were associated with a “non-reactive” attitude, independently from the test condition, confirming an association with a non-aggressive intention. “Head turning” was associated with a “non-reactive” attitude in the threatening condition. In conclusion, dogs with a non-aggressive attitude exhibited more putative appeasement signals; however, these were not strictly associated with a conflict-ridden situation, calling for further investigation of their function.

Behavioural Analysis of Dogs’ Response to Threatening and Neutral Conspecific Video Stimuli

“…Thus, the use of naturalistic videos, including their auditory stimuli was adopted to expose dogs to a standardised conflict-ridden (threatening dog) and non-conflict-ridden (neutral dog) situation and measure the occurrence of displacement behaviours and facial expressions under the two conditions. Although in our previous study with human strangers [20], dogs were not observed to exhibit these behaviours more frequently in a threatening compared to a neutral condition, given the few studies carried out with conspecifics, the predictions for this study were based on the "appeasement signal hypothesis". Hence, it was predicted that dogs would exhibit displacement behaviours more frequently when exposed to videos of conspecifics showing threatening compared to neutral behaviour.…”

“…They found that lip licking was associated with an active submissive attitude in dogs (e.g., ears flattened, tail wagging, crouched posture, greeting behaviour), but was not displayed in highly threatening situations [21]. In a previous study conducted by our research team [20], the threatening approach test (TAT) was adopted to test the dogs' responsiveness to unfamiliar humans approaching them in either a threatening (bent posture and staring) or a neutral (relaxed posture, not staring at the dog) way. In general, the dogs' attitudes in both conditions could be categorised as either reactive or non-reactive (i.e., presence or absence of barking and lunging).…”

“…Results showed that displacement behaviours were not exhibited more in the threatening compared to the neutral condition but were rather associated with the attitude of the dog toward the unfamiliar human. Regardless of condition, "blinking", "nose licking" and "lip wiping" were more likely to occur when dogs did not bark or lunge towards the human, whilst "head turning" was associated with a non-reactive attitude only when the dogs were approached in a threatening way [20].…”

“…Recent studies, in which facial expressions have been analysed with the DogFACS system (an anatomically based system allowing the objective measurement of facial cues [14]), confirmed that facial expressions such as ear movements and mouth-related actions (i.e., nose licking and lip wiping) are dependent on the presence of a social audience and thus possibly used as visual communicative signals (Behavioural Ecology view, [15]) by dogs during dog-human [16,17] and dog-dog interactions. In the dog training literature, displacement behaviours, including self-directed behaviours such as lip licking, yawning, scratching, auto-grooming and environment-directed behaviours, for example, sniffing the environment and drinking, have been suggested to function as de-escalation/appeasement signals in dog-dog as well as dog-human interactions [18,19] (see [20] for a summary of the classification of the displacement behaviours in dogs).…”

Evaluation of indicators of acute emotional states in dogs

“…originating from the throat and mouth 38 Not Whining Sound production ceases 38 Panting Increased shallow respiration through an open mouth, may have tongue out 47 Mouth not visible Can not see mouth area. Panting/Not Panting cannot be determined ( defined for this study ) Not Panting Mouth is closed—normal breathing resumes 38 Yawn An involuntary intake of breath through a wide-open mouth 38 Shake Dog's whole body and/or head starts moving rapidly from side to side while the dog stands 48 Bark Head and lips forward, mouth opening and shutting repeatedly to omit a large, sharp, short sound emitted from the throat 38 Howl Raised muzzle perpendicular to ground and emits a long, drawn-out sound through semi-closed jaws. Stops when dog lowers head and/or when sound is no longer produced ( modified ) 38 …”