Dogs Sense Human Facial Expressions

Dog owners often believe their pets can sense when they are having a bad day. Scientists have found a possible explanation. A study published on August 10 in iScience provides insight into this phenomenon by examining how dogs’ brains react to human facial expressions.

Understanding Dogs’ Brain Responses

Researchers used brain scans to observe pet dogs as they viewed images of people showing emotions like happiness, anger, fear, and sadness. These scans reveal that dogs’ brains react differently depending on the facial expression, suggesting that they do more than sorting faces into broad positive or negative types.

Previous studies indicated dogs can distinguish happy faces from negative ones. However, it was unclear whether they could differentiate between various negative emotions. The new research suggests dogs process emotions such as fear, anger, and sadness differently.

Distinct Patterns for Fearful Faces

The study found that dogs showed different brain activity patterns when presented with fearful faces versus angry or sad ones. This is the first evidence that dogs can differentiate specific negative facial expressions. Fear might be significant because it signals potential dangers, according to researchers Raúl Hernández-Pérez and Laura Cuaya.

Dogs respond differently to odors linked to human fear and happiness. The study, focusing on facial expressions instead of smells, implies that human fear signals have importance to dogs across senses.

Dogs’ Ability to Sense Human Emotions

To investigate, researchers presented eight dogs with photos of strangers displaying happy or neutral expressions while scanning their brains. Happy faces showed increased activity in areas related to cognitive processing and reward.

Notably, the temporal cortex and caudate nucleus became more active when dogs viewed happy faces. Cuaya was surprised to see the caudate nucleus involved in processing these faces. This region in dogs is associated with rewards like food, praise, and the scent of a familiar person.

The caudate nucleus’s involvement suggests that even a happy face from an unfamiliar person might have a positive affective component for dogs, regardless of the animals’ subjective experience.

Expanding the study to include faces expressing happiness, anger, fear, and sadness, researchers used machine-learning techniques to analyze brain scans. They identified patterns linked to these expressions.

Dogs’ responses to happy faces were distinct from their reactions to negative expressions. Fearful faces produced different brain activity patterns compared to angry or sad faces, yet no clear distinction existed between reactions to angry and sad faces.

Therefore, dogs likely do not understand human emotions like humans do. Instead of identifying faces simply as ‘good’ or ‘bad,’ their brains seem to demonstrate unique responses to specific emotional expressions.

Dogs Watching Your Emotions

Evidence suggests dogs are highly attentive to human behavior. Cuaya noted, “While we cannot say that a dog looks at a fearful face and understands it in a human-like conceptual sense, the results indicate their brains do more than simply respond to basic visual properties.” Photographs of unfamiliar individuals were used rather than real-life interactions with owners.

In everyday life, dogs access more indicators of human emotions. When a dog approaches after a rough day, it may detect a range of subtle signals beyond just recognizing a sad face.

Future research is anticipated to explore how dogs combine facial expressions with other information, including vocalizations, body language, and scent.

Dogs’ Social Understanding

Dogs’ ability to relate social cues could stem from their long history of domestication alongside humans. Over millennia, dogs developed social skills aiding communication and cooperation with people.

Research has shown that dogs may change behavior when someone is sad or upset. Real-world situations offer more emotional clues than photographs used in the study.

The study included only 12 dogs, all pets with extensive human interaction. Findings may not apply to dogs with vastly different experiences, such as street dogs.

Nonetheless, the study provides insight into the sensitivity of dogs to human emotions.
While dogs may not understand emotions like sadness or happiness the same way humans do, their brains are attuned to emotional signals visible on faces.

Cuaya underscored the significance of emotions as an essential communication channel working in both directions.

Citation: Raúl Hernández-Pérez, Luis Concha, Attila Andics, Rodolfo Bernal-Gamboa, Laura V. Cuaya. Dog brain representations of human facial expressions: Encoding happiness and differentiating specific negative expressions. iScience, 2026; 116900 DOI: 10.1016/j.isci.2026.116900

For further information, the Newsweek editors Marc Vargas and Emma Lee-Sang may be contacted in relation to this study.