New Brain Scans Show Dogs Can Tell Fear From Sadness on Our Faces

RESEARCH & INNOVATION

fMRI research on awake, unrestrained dogs offers the first evidence that canine brains distinguish between specific negative human expressions, not just good faces from bad ones.

Anyone who has worked a rough shift in exam rooms already suspects dogs pick up on more than we give them credit for. Now there is brain imaging to back it up. A study published Aug. 7 in the Cell Press journal iScience used fMRI to look inside the brains of pet dogs as they viewed images of human faces expressing happiness, anger, fear, and sadness, and found real neural evidence that dogs process these expressions in distinct ways.

The research team, led by first author Raul Hernandez-Perez and senior author Laura Cuaya, both of the University of Vienna, built on work Cuaya began at the National Autonomous University of Mexico and later expanded through a collaboration with Eotvos Lorand University in Hungary.

Humans are really good at picking up small details on the face, and so are dogs, said Hernandez-Perez. This makes dogs very interesting. By studying their brains, we can understand what adaptations have developed to support their remarkable social and emotional understanding of humans.

Starting With Happiness

The researchers first scanned eight dogs while showing them images of strangers with either happy or neutral expressions. Happy faces activated the temporal cortex and caudate nucleus, brain regions tied to higher cognitive processing and reward, respectively. Cuaya noted that the caudate nucleus activity in particular suggests happy human faces may carry real emotional significance for dogs, not just visual novelty.

Then Testing the Negative Expressions

The team expanded the study to 12 dogs and showed them images of people displaying happiness, anger, fear, and sadness, analyzing the resulting brain activity with machine learning. The temporal cortex-caudate nucleus network that lit up for happiness did not respond the same way to any of the three negative expressions, which let researchers cleanly separate happy reactions from negative ones in the data.

The more striking finding came next. A whole-brain analysis showed distinct activity patterns that separated fear from anger and sadness, the first evidence that dogs' brains distinguish between specific negative human expressions rather than lumping all non-happy faces into one generic bad-feeling category.

What This Doesn't Mean

The researchers were careful to flag the limits of the findings. This ability does not necessarily mean dogs experience emotions the way humans do, and a still photograph only captures part of what a dog would normally pick up on. In real interactions, dogs are also reading body language, vocal tone, and scent, all of which the fMRI study could not account for.

It is also worth noting that all of the dogs in the study were pets from loving homes. The team pointed out that free-ranging or street dogs navigate a very different social world and may process human facial cues differently, which leaves an open question for future research.

An Evolutionary Angle Worth Sitting With

When we compare humans with primates, we are looking at abilities that may have come from a common ancestor, Cuaya said. With dogs, the story is totally different. They followed a very different evolutionary path, yet through domestication, they developed the social abilities needed to understand and cooperate with us.

That framing is part of what makes this research land differently than similar work in primates. Dogs did not inherit social-cognitive machinery from a shared ancestor with humans; whatever ability they have to read our expressions was shaped by thousands of years of domestication and cohabitation instead.

What's Next

The researchers plan to take a more dog-centric approach going forward, studying how dogs integrate these brain signals to make sense of the humans around them, and eventually comparing how human and dog brains process the same emotional cues side by side.

Cuaya summed up the practical takeaway for anyone who lives or works with dogs: recognizing dogs as emotional beings, capable of picking up on the nuance in our expressions, can change how we communicate with and care for them. For veterinary professionals, that is a useful reminder that the dog on the exam table may be reading the room, and the humans in it, more precisely than we tend to assume.

Source: Hernandez-Perez, R. et al., "Dog brain representations of human facial expressions," iScience (2026), DOI: 10.1016/j.isci.2026.116900; Cell Press news release, Aug. 10, 2026.