Study shows dogs' brains reward them for seeing human smiles

A recent functional-MRI study involving 14 dogs demonstrated that images of happy, smiling humans activate a reward-related brain region, the same circuitry that responds to food or praise. The researchers, Laura Cuaya and Raúl Hernández-Pérez, also examined dogs' reactions to angry, fearful and sad faces, finding no comparable activation, which implies dogs can tell positive emotions apart from negative ones but not the nuances among the latter.

The team recruited participants from local dog parks, using dogs that fit the scanner size and were well-trained. Their own border collies, Odín and Kun-kun, took part in the experiment. The findings, appearing in the journal iScience, highlight how domestication may have reshaped canine neural pathways to attune them to human emotional signals. Cuaya suggests that smiling at dogs, even strangers, can reinforce positive interactions.