Smiling Human Faces Are Attractive to Dogs, Thanks to Oxytocin

Summary: A new study reveals oxytocin, a hormone implicated in bonding, may play an important role in social interactions between man and dog.

Source: University of Helsinki.

Researchers in the University of Helsinki’s Canine Mind research project found that oxytocin made dogs interested in smiling human faces. It also made them see angry faces as less threatening. Associated with affection and trust, the hormone oxytocin is probably a key factor in the interaction between dogs and humans.

“It seems that the hormone oxytocin influences what the dog sees and how it experiences the thing it sees,” says doctoral student Sanni Somppi.

Researchers in the Canine Mind group showed 43 dogs images of smiling and angry faces on a computer screen. Each dog was tested twice: once under the influence of oxytocin, which was administered as part of the test, and once without oxytocin. The dog’s gaze on the images and pupil size were measured with an eye-tracking device. Emotions and attentiveness guide the gaze and regulate pupil size, making eye tracking a window into the dogs’ minds.

Dogs typically focus on the most remarkable aspect of each situation, such as threatening stimuli in a frightening situation. Recognising and interpreting threats quickly is important for survival. Dogs under the influence of oxytocin were more interested in smiling faces than they were in angry ones.

In addition, oxytocin also influenced the dogs’ emotional states, which was evident in their pupil size.

“We were among the first researchers in the world to use pupil measurements in the evaluation of dogs’ emotional states. This method had previously only been used on humans and apes,” says Professor Outi Vainio, who heads the research group.

a dog and people

Oxytocin is probably a key factor in the interaction between dogs and humans NeuroscienceNews.com image is credited to the researchers.

Without oxytocin, the dogs’ pupils were at their largest when they looked at angry faces. This indicated that the angry faces caused the most powerful emotional reaction in the dogs. Under the influence of oxytocin, however, images of smiling faces enhanced the dogs’ emotional state more than angry ones. This is to say that oxytocin probably made the angry faces seem less threatening and the smiling faces more appealing.

“Both effects promote dog–human communication and the development of affectionate relations,” says Professor Vainio.

About this neuroscience research article

Professor Vainio’s research group has previously successfully applied eye tracking and EEGs to studying the canine mind. In this study, the group partnered with József Topál, a Hungarian pioneer of canine research who specialises in dog–human interaction and the social intelligence of dogs.

Source: Sanni Somppi – University of Helsinki
Publisher: Organized by NeuroscienceNews.com.
Image Source: NeuroscienceNews.com image is credited to the researchers.
Original Research: Full open access research for “Nasal Oxytocin Treatment Biases Dogs’ Visual Attention and Emotional Response toward Positive Human Facial Expressions” by Sanni Somppi, Heini Törnqvist, József Topál, Aija Koskela, Laura Hänninen, Christina M. Krause and Outi Vainio in Frontiers in Psychology. Published online October 17 2017 doi:10.3389/fpsyg.2017.01854

Cite This NeuroscienceNews.com Article
University of Helsinki “Smiling Human Faces Are Attractive to Dogs, Thanks to Oxytocin.” NeuroscienceNews. NeuroscienceNews, 25 November 2017.
<http://neurosciencenews.com/oxytocin-dog-smiling-8029/>.
University of Helsinki (2017, November 25). Smiling Human Faces Are Attractive to Dogs, Thanks to Oxytocin. NeuroscienceNews. Retrieved November 25, 2017 from http://neurosciencenews.com/oxytocin-dog-smiling-8029/
University of Helsinki “Smiling Human Faces Are Attractive to Dogs, Thanks to Oxytocin.” http://neurosciencenews.com/oxytocin-dog-smiling-8029/ (accessed November 25, 2017).

Abstract

Nasal Oxytocin Treatment Biases Dogs’ Visual Attention and Emotional Response toward Positive Human Facial Expressions

The neuropeptide oxytocin plays a critical role in social behavior and emotion regulation in mammals. The aim of this study was to explore how nasal oxytocin administration affects gazing behavior during emotional perception in domestic dogs. Looking patterns of dogs, as a measure of voluntary attention, were recorded during the viewing of human facial expression photographs. The pupil diameters of dogs were also measured as a physiological index of emotional arousal. In a placebo-controlled within-subjects experimental design, 43 dogs, after having received either oxytocin or placebo (saline) nasal spray treatment, were presented with pictures of unfamiliar male human faces displaying either a happy or an angry expression. We found that, depending on the facial expression, the dogs’ gaze patterns were affected selectively by oxytocin treatment. After receiving oxytocin, dogs fixated less often on the eye regions of angry faces and revisited (glanced back at) more often the eye regions of smiling (happy) faces than after the placebo treatment. Furthermore, following the oxytocin treatment dogs fixated and revisited the eyes of happy faces significantly more often than the eyes of angry faces. The analysis of dogs’ pupil diameters during viewing of human facial expressions indicated that oxytocin may also have a modulatory effect on dogs’ emotional arousal. While subjects’ pupil sizes were significantly larger when viewing angry faces than happy faces in the control (placebo treatment) condition, oxytocin treatment not only eliminated this effect but caused an opposite pupil response. Overall, these findings suggest that nasal oxytocin administration selectively changes the allocation of attention and emotional arousal in domestic dogs. Oxytocin has the potential to decrease vigilance toward threatening social stimuli and increase the salience of positive social stimuli thus making eye gaze of friendly human faces more salient for dogs. Our study provides further support for the role of the oxytocinergic system in the social perception abilities of domestic dogs. We propose that oxytocin modulates fundamental emotional processing in dogs through a mechanism that may facilitate communication between humans and dogs.

“Nasal Oxytocin Treatment Biases Dogs’ Visual Attention and Emotional Response toward Positive Human Facial Expressions” by Sanni Somppi, Heini Törnqvist, József Topál, Aija Koskela, Laura Hänninen, Christina M. Krause and Outi Vainio in Frontiers in Psychology. Published online October 17 2017 doi:10.3389/fpsyg.2017.01854

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