Dogs can distinguish between different human emotions by processing facial expressions, according to research from the University of Vienna that provides new evidence of how dogs interpret human behavior.

Researchers scanned the brains of 12 dogs while showing them photographs of unfamiliar people displaying different facial expressions, including happiness, fear, anger and sadness.

Machine-learning analysis showed that two brain areas linked to higher cognitive processing and reward responses—the temporal cortex and caudate nucleus—were activated when the dogs viewed happy human faces.

The researchers also identified different patterns of brain activity when the dogs were shown fearful, angry and sad expressions. This indicates that the animals can distinguish between different negative emotions rather than responding to them as a single category.

The findings were published in iScience and provide neurological evidence that dogs can differentiate specific human facial emotions.

Researchers said dogs’ long history of living alongside humans may have helped them develop the ability to interpret human emotional signals.

The team will next study whether dogs combine facial expressions with other information, including body movements, voice and smell, when assessing human emotions.

Researchers also plan to compare canine and human brain responses to the same emotional signals.

The study involved household dogs raised in caring environments, and the researchers cautioned that dogs with different backgrounds may respond differently to human emotional cues.