Dogs have spent thousands of years living alongside humans. Apparently, they have been paying very close attention. New research has found that dogs’ brains respond differently to different human facial expressions, including distinctions between some negative expressions such as fear, sadness and anger. This goes considerably further than recognising that a smiling person is probably preferable to an angry one.
The study, provides the first neural evidence that dogs can distinguish between two human faces displaying different negative expressions. In other words, their brains are not simply sorting our faces into a crude system of “good” and “bad”.
Dogs Are Reading Our Faces
Researchers conducted 2 experiments using functional magnetic resonance imaging, or fMRI, which allowed them to examine brain activity while awake dogs looked at photographs of human faces.
In the first experiment, 8 dogs were shown happy and neutral faces. Happy faces produced stronger activity in a region centred in the right temporal cortex and extending into the caudate nucleus. That is particularly interesting because previous research discussed by the authors has associated the caudate nucleus with rewarding stimuli, including food and familiar scents.
The researchers suggest that happy human faces may therefore be rewarding to dogs, even when the smiling person is a complete stranger.
The second experiment involved 12 dogs looking at people displaying happiness, anger, fear and sadness. Using machine learning, researchers could distinguish dogs’ neural responses to happiness from their responses to each of the three negative expressions. But the most interesting result came when they examined activity across the entire brain. Dogs showed distinguishable brain patterns when looking at fearful compared with sad faces, and fearful compared with angry faces. The researchers did not find the same distinction between anger and sadness.
Fear, in particular, may be highly significant to dogs. The study discusses previous research showing that dogs respond differently to fearful faces, fear-related sounds and even chemical signals associated with human fear. Puppies have also been found to respond distinctly to fear-related human scents. Perhaps knowing when the strange primate you live with is frightened has its advantages.
More Than Memorising
This finding joins a growing body of research revealing just how much information some dogs extract from humans. A separate 2025 study examined seven dogs described as “gifted learner dogs”, six border collies and one blue heeler. They had learned labels associated with toys through ordinary interactions and play. Researchers then asked them to choose unfamiliar toys according to whether they were used for “pull” or “fetch”.
Remarkably, the dogs could extend those labels to new objects based on their function, even when the toys looked different. This ability, known as label extension, is important in early human language development. The researchers were careful not to claim dogs possess human language, but the result suggests that at least some dogs can do considerably more than memorise sounds associated with individual objects. They can extract something closer to meaning.
Meanwhile, Humans Keep Getting Dogs Wrong
Dogs are extraordinarily good at interpreting us. We are not necessarily returning the favour. Research published in 2025 surveyed 224 current and former companion animal guardians about common beliefs concerning cats and dogs. Some misconceptions remained remarkably common.
Around 42% believed dogs need to know who is in charge. A third believed a wagging tail means a dog is happy. Almost another third thought dogs love being hugged. Even ideas rooted in outdated dominance theories survived, with 27% believing humans should walk through a doorway before their dog.
These misconceptions are not always harmless. If fear, pain or illness is interpreted as stubbornness or deliberate misbehaviour, the response can be punishment rather than help. Humans can love dogs enormously while still misunderstanding what dogs are trying to tell us.
Dogs appear capable of examining our faces, voices, bodies and smells for information about how we feel. Some can learn words well enough to apply them to entirely unfamiliar objects.
And we are still arguing about whether a wagging tail automatically means “happy”.
We Have More To Learn
There are important limitations to the new brain study. Only 12 dogs participated in its second experiment, and border collies made up most of the sample. The researchers explicitly caution against assuming every breed processes human expressions in exactly the same way. The dogs also viewed static photographs, while real social interactions involve movement, voices, body language and smell. Nor does different brain activity prove that dogs understand concepts such as “sadness” or “fear” exactly as humans do. The researchers are explicit about that.
But we do not need to turn dogs into little furry humans for the findings to be remarkable. Their brains are sensitive to subtle differences in our emotional expressions. Their understanding of us is sophisticated, socially important and still being uncovered. Perhaps the more uncomfortable question is how much effort we have made to understand them.
I'm glad to read this. I spent a great deal of time smiling lovingly to my dog companion during her last days and I only hope she knew how much love I was trying to send her.