# Behavioural Analysis of Dogs' Response to Threatening and Neutral Conspecific Video Stimuli +
Footnote †: _Applied_  
been associated with frustration, the ears adductor action has been associated with positive anticipation [11; 12]. Traditionally, facial expressions such as ear flattening, and lip liking have been considered submissive/appeasement signals used by both wild canids and domestic dogs to appease the receiver and reduce the probability of potentially aggressive behaviours [13]. 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 liking 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 liking, 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). One prediction based on the appeasement function of the displacement behaviours hypothesis is that these behaviours should be exhibited more in conflict-ridden compared to non-conflict-ridden situations. However, the few scientific studies that have been carried out have shown mixed results. At the interspecific level, [PERSON] and colleagues [21] investigated whether the display of lip liking was more frequent in dogs when exposed to a human approaching with a highly threatening, mild threatening or friendly attitude as well as different environmental stressors. They found that lip liking 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 liking\" and \"lip wiping\" were more likely to occur when dogs did not bark or lung towards the human, whilst \"head turning\" was associated with a non-reactive attitude only when the dogs were approached in a threatening way [20]. At the intraspecific level, [PERSON] and colleagues [6] showed that dogs never exhibited putative appeasement signals (including the displacement behaviours of head turning, nose liking and paw lifting) before aggressive episodes but, if an aggressive interaction occurred, the probability of re-aggression was decreased if these behaviours were exhibited. The latter study, however, did not consider instances in which threatening interactions did not turn into aggression, thus it was not possible to evaluate whether putative appeasement signals could prevent the escalation from threat to aggressive interaction. Applying a TAT paradigm for dog-dog interactions would enable the testing, with a standardised procedure, of whether these behaviours are exhibited more towards a threatening conspecific before an aggressive interaction occurs.