Summary: A new study shows that dogs use different brain hemispheres to process negative and positive emotional cues from human facial expressions.
Source: Springer.
Dogs can read human faces and respond differently to emotions such as anger, fear, happiness and surprise. In a controlled experiment, researchers observed that dogs turn their heads and show distinct changes in heart rate depending on the emotion displayed, and that these responses are linked to lateralized processing in the canine brain. The findings, reported by Marcello Siniscalchi, Serenella d’Ingeo and Angelo Quaranta from the University of Bari Aldo Moro and published in the journal Learning & Behavior, add to evidence that living closely with people has tuned dogs’ perception and emotional sensitivity.
Domestic dogs have evolved social and perceptual skills that help them interact with humans. Previous research has demonstrated that dogs pick up emotional cues from human vocalizations, body odor and posture, and that they can interpret facial expressions. The current study focused specifically on how dogs orient themselves and how their physiology responds when they see human faces expressing basic emotions.
In the experiment, the researchers presented 26 feeding dogs with two-dimensional photographs of the same two adult faces (one man and one woman). Each image showed one of the basic human emotions: anger, fear, happiness, sadness, surprise, disgust or a neutral expression. The photographs were displayed to the dogs’ left and right visual fields to test hemispheric processing while the dogs were engaged in feeding.
When dogs viewed images showing arousing emotional states—anger, fear or happiness—they reacted more strongly. These reactions included turning their heads to the left, showing greater behavioral disturbance and exhibiting increased heart rates. Dogs also took longer to resume feeding after seeing these arousing expressions, indicating heightened physiological and attentional responses. By contrast, images of surprised faces typically elicited a head turn to the right and were treated by dogs as less threatening or arousing.
The pattern of head-turning and the associated cardiac changes support the idea of hemispheric specialization in the canine brain. The researchers interpret the leftward head bias—indicating right-hemisphere dominance—as a response to clearly arousing or negative emotions. Conversely, the rightward head bias for surprise points to left-hemisphere involvement when dogs process less threatening, more relaxed expressions. These lateralized responses mirror findings in other mammals and suggest that the canine brain differentiates emotional valence and arousal using distinct neural circuits.
Heart rate increases recorded during exposure to arousing expressions further underscore an autonomic component to dogs’ emotional processing. The right hemisphere is known to play a critical role in sympathetic regulation, which governs the ‘fight or flight’ response. The study’s cardiac measurements are therefore consistent with a biologically meaningful link between perceived emotional threat or arousal in humans and dogs’ own physiological and behavioral reactions.
The research contributes to a growing body of evidence that dogs are finely attuned to human emotional signals. Understanding how dogs process human facial expressions has practical implications for improving dog–human communication, training methods, and animal welfare. It also offers comparative insight into how social mammals, including humans, process emotional information across the two hemispheres of the brain.
Source: Erica Lorenzoni – Springer
Publisher: Organized by NeuroscienceNews.com.
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Original Research: Abstract for “Orienting asymmetries and physiological reactivity in dogs’ response to human emotional faces” by Marcello Siniscalchi, Serenella d’Ingeo, and Angelo Quaranta in Learning & Behavior. Published June 19, 2018.
doi: 10.3758/s13420-018-0325-2
Springer. “Dogs Understand What’s Written All Over Your Face.” NeuroscienceNews. Published June 20, 2018.
Abstract
Orienting asymmetries and physiological reactivity in dogs’ response to human emotional faces
Recent literature indicates that emotional cues from human vocalizations and odors are processed asymmetrically in the canine brain. In this study, dogs feeding were presented with 2-D images of human faces that displayed Ekman’s basic emotions (anger, fear, happiness, sadness, surprise, disgust, and neutral) in the left and right visual hemifields. Dogs showed a bias to turn their heads to the left—reflecting right-hemisphere processing—when viewing faces expressing anger, fear and happiness. An opposite bias toward the right—reflecting left-hemisphere processing—was observed for surprised faces. Dogs also displayed higher behavioral and cardiac reactivity when viewing faces that conveyed clearly arousing emotional states. These results indicate that dogs are sensitive to human facial emotional cues and that their brains process basic human emotions in an asymmetrical, lateralized manner.