The Way Dogs (Canis familiaris) Look at Human Emotional Faces Is Modulated by Oxytocin. An Eye-Tracking Study

Abstract

Dogs have been shown to excel in reading human social cues, including facial cues. In the present study we used eye-tracking technology to further study dogs’ face processing abilities. It was found that dogs discriminated between human facial regions in their spontaneous viewing pattern and looked most to the eye region independently of facial expression. Furthermore dogs played most attention to the first two images presented, afterwards their attention dramatically decreases; a finding that has methodological implications. Increasing evidence indicates that the oxytocin system is involved in dogs’ human-directed social competence, thus as a next step we investigated the effects of oxytocin on processing of human facial emotions. It was found that oxytocin decreases dogs’ looking to the human faces expressing angry emotional expression. More interestingly, however, after oxytocin pre-treatment dogs’ preferential gaze toward the eye region when processing happy human facial expressions disappears. These results provide the first evidence that oxytocin is involved in the regulation of human face processing in dogs. The present study is one of the few empirical investigations that explore eye gaze patterns in naïve and untrained pet dogs using a non-invasive eye-tracking technique and thus offers unique but largely untapped method for studying social cognition in dogs.

Perception of dynamic facial expressions of emotion between dogs and humans

“…Our results are in contrast with one potentially comparable study using static images (Kis et al 2017), where the human eyes and mouth were attended to more, but partially agree with Barber et al (2016) where the human mouth and cheeks + nose (i.e., AOI "face rest") were fixated on more than the rest of the face. Kis et al (2017) argued that the forehead was less informative, which appears inconsistent from both an anatomical and communicative stance (e.g., the eyebrow flash, Eibl-Eibesfeldt 1972; or expression of fear, Ekman et al 2002b). The frontalis muscle produces conspicuous changes on the forehead (Ekman et al 2002a), by pulling the eyebrows and hairline upwards, and wrinkling the forehead (AU1 + AU2).…”

“…The lower attention towards the eyes from dog observers might alternatively (or additionally) stem from the functional significance of eye contact in dogs compared to humans. While humans engage in prolonged eye gaze for mostly positive reasons (e.g., emotion perception, communicative intent, Senju and Csibra 2008;Kis et al 2017), with lack of eye contact interpreted negatively (Larsen and Shackelford 1996), in canids, and many other species, a fixed stare is linked to agonistic contexts (McGreevy et al 2012;Kis et al 2017).…”

Heart Rate and Heart Rate Variability during Sleep in Family Dogs (Canis familiaris). Moderate Effect of Pre-Sleep Emotions

“…This makes them further valuable as a model system, since due to the increasing scientific interest in the species [ 26 ], considerable amount of information has accumulated on their behaviour and neurocognition [ 27 ]. Extensive data exists about dogs’ emotional processing, for example showing that they spontaneously distinguish between human emotions based on facial expressions [ 28 , 29 , 30 , 31 ]. Furthermore, dogs are able to base their in-test choices on human emotional expressions [ 32 , 33 ].…”

Training pet dogs for eye-tracking and awake fMRI

“…In five studies, the focus was on the dog's response to emotional expressions. Researchers asked whether dogs show an attentional bias toward threatening social stimuli and whether their gaze fixation patterns are influenced by the different facial areas of human and dog faces (Somppi et al, 2016), how dogs with different experience with humans (pet vs. laboratory dogs) scan human emotional faces (Barber, Müller, Randi, Müller, & Huber, 2017;Barber et al, 2016;), whether oxytocin has an impact on the processing of human facial emotions (Kis, Hernádi, Miklósi, Kanizsár, & Topál, 2017;Somppi et al, 2017), and whether the latter effect correlates with cardiac responses (Barber et al, 2017). Most recently, researchers have investigated con-and heterospecific auditory-visual matching in dogs when seeing a woman's face and hearing her voice or seeing a dog's face and hearing its barking (Gergely, Petró, Oláh, & Topál, 2019).…”