Can my human read my flat face? The curious case of understanding the contextual cues of extremely brachycephalic dogs

Abstract

Canine visual signals convey contextual and affective information to the humans. Besides previous experience with dogs, another factor that could hinder the efficacy of dogs’ visual signals is the development of such extreme features through artificial selection which directly affect the signalling capacity of dogs. Brachycephaly is one of the most prevalent extreme features in particular dog breeds. The exaggeratedly shortened muzzle region of these dogs not only enhances their ‘cuteness’ in the eyes of the fancier, but severely compromises the animal’s health and according to our prediction, it also may affect the way how human observers would decipher a brachycephalic dog’s facial expressions. So far, this question has not been investigated, therefore we ran a novel experiment where human participants had to guess the context of various communicative interactions with several representatives of a brachycephalic breed (Boston Terriers) and a normocephalic breed (Jack Russell Terriers). Participants were provided with short, soundless video clips and still portrait shots of the dogs in an online survey. We used four original contexts for recording the presentation materials: “Called by name”; “Play”; “Separation”; “Threatened by stranger”. Accuracy of contextual recognition depended on the type of source (P<0.001). Participants in general were more successful in the case of Bostons when the context was ‘positive’ (“Called by name”, “Play”), while ‘negative’ contexts (“Separation”, “Threatened by stranger”) were more likely recognised in case of Jack Russells. When comparing the valence of assigned contextual signals (P<0.001), Bostons were more often assigned with ‘positive’ contexts based on video clips than on still pictures. No such difference was found in the Jack Russells. While evaluating the videos and pictures, participants more likely based their decision on the face and tail in case of the Jack Russells, but preferred to use the torso of the Bostons for contextual information (P<0.001). These are the first empirical results about the potentially reduced signalling potential of brachycephalic dogs’ facial expressions. Our study showed that in the case of Boston Terriers, human observers tend to assign ‘positive, happy’ message to these dogs, and instead of the facial region, they may tend to rely on the body language of these dogs when interacting with them.