Date Published: January 23, 2017
Publisher: Public Library of Science
Author(s): Miiamaaria V. Kujala, Sanni Somppi, Markus Jokela, Outi Vainio, Lauri Parkkonen, Elisabetta Palagi.
Facial expressions are important for humans in communicating emotions to the conspecifics and enhancing interpersonal understanding. Many muscles producing facial expressions in humans are also found in domestic dogs, but little is known about how humans perceive dog facial expressions, and which psychological factors influence people’s perceptions. Here, we asked 34 observers to rate the valence, arousal, and the six basic emotions (happiness, sadness, surprise, disgust, fear, and anger/aggressiveness) from images of human and dog faces with Pleasant, Neutral and Threatening expressions. We investigated how the subjects’ personality (the Big Five Inventory), empathy (Interpersonal Reactivity Index) and experience of dog behavior affect the ratings of dog and human faces. Ratings of both species followed similar general patterns: human subjects classified dog facial expressions from pleasant to threatening very similarly to human facial expressions. Subjects with higher emotional empathy evaluated Threatening faces of both species as more negative in valence and higher in anger/aggressiveness. More empathetic subjects also rated the happiness of Pleasant humans but not dogs higher, and they were quicker in their valence judgments of Pleasant human, Threatening human and Threatening dog faces. Experience with dogs correlated positively with ratings of Pleasant and Neutral dog faces. Personality also had a minor effect on the ratings of Pleasant and Neutral faces in both species. The results imply that humans perceive human and dog facial expression in a similar manner, and the perception of both species is influenced by psychological factors of the evaluators. Especially empathy affects both the speed and intensity of rating dogs’ emotional facial expressions.
Facial expressions play an important part in nonverbal social communication among us humans (for reviews, see e.g. [1,2]) as among other mammals (for reviews, see [3,4]). Human sensitivity for others’ facial expressions facilitates better comprehension of the emotions, moods, attitudes and aims of the conspecifics. Likewise, humans also pay attention to the emotional expressions of non-conspecifics. Domestic dogs (Canis familiaris) are of special interest in this context, since they have underwent a long domestication with humans [5,6] and have excellent social communication skills (e.g. ). Furthermore, dogs have many of the same muscles that produce facial expressions in humans , and their facial expressions are connected to the affective situation . Dogs can differentiate emotions displayed by either human or dog facial expressions [10–12], and they also show rapid facial mimicry in response to a conspecific expression during play . Facial expressions thus provide important information of conspecific emotions also for dogs; they reflect at least some of their emotional states by the face and react to others’ expressions accordingly.