Work package 1: Empathy in dogs

Empathy, basically defined as the sharing of others’ emotional states, requires the assessment and measurement of the emotional states of subjects. To this end we attempted to use several state-of-the-art techniques to measure the strength and the valence of the emotional state of dogs when confronted with suitable, highly-controlled stimuli (from either conspecifics or humans). The question of whether animals have emotions and respond to the emotional expressions of others has become a focus of research in the last decade. Neurobiologists and psychologists have conceptualized emotion as a concerted, generally adaptive, phasic change in multiple physiological systems (including both somatic and neural components) in response to the value of a stimulus.

 
 [Link 1]

Müller, E. (2014) Heart rate variability in dogs during exposure to emotional human facial expressions. Diploma Thesis, University of Veterinary Medicine Vienna.

The aim was to investigate whether dogs react with an altered heart rate and heart rate variability while being confronted with different emotional facial expressions of humans and if the presented emotions induce characteristic pattern in the cardiac activity. For this purpose, videos containing either happy, angry, sad or neutral faces were shown to 13 pet dogs. These same expressions were demonstrated live by the owner. Before and after the testing phase baselines were recorded.The recording of the heart rate was conducted with the non-invasive portable device Polar® RS800CX. In the univariate analyses of variance none of the investigated cardiac parameters showed significant differences to the emotional stimuli. Rather it has been found that stimulus duration has a significant decreasing effect on heart rate (p=0.010) and increasing effect on heart rate variability (p=0.001). The results showed that several influences on the heart rate are likely to overshadow emotional responses.

Photo: Anjuli Barber/Vetmeduni Vienna

 
 [Link 2]

Randi, D. (2015)
 Human emotion recognition in laboratory beagles. Master Thesis, University of Zagreb.

This project explored the ability of laboratory dogs (breed: beagle) to respond to emotions expressed in human faces. These dogs have been raised at the Vetmeduni Vienna in conditions of limited interaction with humans. The main question was the possible influence of emotion and familiarity of human faces on both the visual attention and the heart rate of laboratory beagles. Eye movements (with eye-tracking) have been measured and heart rate changes. It has been found that the familiarity of person presented on picture plays an important role, and that the area of eyes and mouth of the human face are the strongest attention attractors. The beagles were able to direct the attention to the important parts of human face, which suggests that the ability of perception and recognition of human emotions expressed in faces is in the species, and is gradually enhanced through the process of socialization. Concerning the heart rate measurements, it has been found the dogs not systematically and reliably reacting to the human emotional stimuli. HRV showed strong inter-individual variance, possibly caused by varying daily constitutions of the dog. A habituation effect indicated that dogs got used to the repeated presentation of humans emotions.

Photo: Dania Randi/Vetmeduni Vienna

 
 [Link 3]

Barber, A. L. A., Randi, D., Müller, C. A., & Huber, L. (2016). The processing of human emotional faces by pet and lab dogs: evidence for lateralization and experience effects. PLoS ONE, 11(4), e0152393. doi:10.1371/journal.pone.0152393 

The eye-tracking experiment aimed at measuring the dog's looking behavior towards human faces that are shown in different emotional expressions (happy, angry, sad and neutral).The dogs were shown pictures of familiar and unfamiliar human faces expressing four different emotions. The results, extracted from several different eye-tracking measurements, revealed pronounced differences in the face processing of pet and lab dogs, thus indicating an influence of the amount of exposure to humans. In addition, there was some evidence for the influences of both, the familiarity and the emotional expression of the face, and strong evidence for a left gaze bias.These findings, together with recent evidence for the dog's ability to discriminate human facial expressions, indicate that dogs are sensitive to some emotions expressed in human faces.

Photos: Anjuli Barber/Vetmeduni Vienna

 
 [Link 4]

Müller, C. A., Schmitt, K., Barber, A. L. A., & Huber, L. (2015). Dogs Can Discriminate Emotional Expressions of Human Faces. Current Biology, 25, 1–5. doi:http://dx.doi.org/10.1016/j.cub.2014.12.055

Pet dogs were tested in a forced two-choice task on the touchscreen. After a pre-training and then learning to discriminate between happy and angry human faces in 15 picture pairs, whereby for one group only the upper halves of the faces were shown and for the other group only the lower halves of the faces were shown, dogs were tested with four types of probe trials: (1) the same half of the faces as in the training but of novel faces, (2) the other half of the faces used in training, (3) the other half of novel faces, and (4) the left half of the faces used in training. It has been found that dogs for which the happy faces were rewarded learned the discrimination more quickly than dogs for which the angry faces were rewarded. This would be predicted if the dogs recognized an angry face as an aversive stimulus. Furthermore, the dogs performed significantly above chance level in all four probe conditions and thus transferred the training contingency to novel stimuli that shared with the training set only the emotional expression as a distinguishing feature. It has been concluded that the dogs used their memories of real emotional human faces to accomplish the discrimination task.

Photo:Anjuli Barber/Vetmeduni Vienna

 

Huber, A. (2015) Empathic-like responding in dogs (Canis familiaris) to emotional sounds of humans and conspecifics. Master Thesis, University of Veterinary Medicine Vienna.

In this study a playback experiment has been applied to investigate whether dogs differentiate between emotional sounds of humans and conspecifics and non-emotional sounds of the dogs' natural environment. Furthermore, it analysed how dogs responded towards the emotional stimuli and whether their behaviour differed dependent on species or valence of the stimulus. For a response interpreted as emotional contagion, the emotional tone of the dogs' behaviour has to correspond to the valence of the emotional sound. Thus, in response to emotionally negative sounds, the 53 pet dogs should express behaviours indicating negative emotions; this should not be the case for positive emotional sounds. The results indicated that, overall, the dogs differered in their behavioural response between emotional and non-emotional sounds. Although the response towards human and dog stimuli was similar, the latter seemed more likely to induce social tension in the subjects. The dogs' behaviour indicated emotional state-matching, at least for negative sounds of both species, which suggests emotional contagion.

Photo: Annika Huber/Vetmeduni Vienna

 
 [Link 5]

Färber, V. (2015) Investigating emotional contagion in domestic dogs (Canis familiaris). Master Thesis, University of Vienna.

The study used a playback design to examine whether dogs are affected by the emotions of their conspecifics. In this experiment conspecifics’ vocalizations (whines) has been recorded during a distressful event as well as control sounds. The subjects from sixteen dog pairs of various breeds were first exposed to a playback phase where they were subjected either to a control sound, a familiar whine (from their familiar partner) or a stranger whine stimulus (from a stranger dog), and then a reunion phase where the familiar partner entered the room. When exposed to whines, dogs showed a higher behavioral alertness and exhibited more stress-related behaviors compared to when exposed to acoustically similar control sounds. Moreover, they demonstrated more comfort-offering behaviors toward their familiar partners following whine playbacks than after control stimuli. Furthermore, when looking at the first session, this comfort offering was biased towards the familiar partner when subjects were previously exposed to the familiar compared to the stranger whines. Finally, familiar whine stimuli tended to maintain higher cortisol levels while stranger whines did not. To our knowledge, these results are the first to suggest that dogs can experience and demonstrate “empathic-like” responses to conspecifics’ distress-calls. 

Photo: Viola Färber/Vetmeduni Vienna