MRI Scans Prove Dogs Can Read Your Face, And Smiling At Them Lights Up Their Reward Center

Researchers at the University of Vienna and Eötvös Loránd University in Budapest trained pet dogs to lie still inside an MRI scanner while awake, wearing earmuffs, resting their chins on a support, and retaining the ability to get up and leave at any time, then showed them photographs of human faces displaying different emotions and measured which parts of the dogs' brains responded. The study, published in the journal iScience, ran in two parts. In the first, eight dogs saw photographs of strangers showing either a blank expression or a smile. The smiling faces produced significantly more activity than the blank ones across a large area on the right side of the brain, and that activity extended down into the caudate nucleus, a deep brain structure that in earlier dog experiments responded to food rewards and to the familiar smell of their owners. Lead researcher Laura Cuaya described the caudate nucleus finding as particularly interesting, saying it suggests that happy human faces may have genuine emotional significance for dogs beyond simple visual recognition. In the second experiment, twelve dogs were shown four different emotional expressions: happiness, anger, fear, and sadness. A computer program trained on the happy-face brain regions correctly identified a happy face versus a sad one about seven times out of ten, well above chance.

The more striking finding came when the researchers looked at the brain's responses to two negative emotions placed against each other. Fear and anger, it turned out, activated different brain regions. One spot on the right side of the brain distinguished fear from sadness, and two more spots could tell anger from fear. No region anywhere in the brain separated sad faces from angry ones, a finding Cuaya called exciting because it is the first evidence that the dog brain can differentiate between two negative human emotions at the neural level. The researchers cannot yet explain exactly why fear was the emotion most consistently set apart from the others, though one possible explanation involves attention: earlier studies have shown that dogs pay more attention to frightened human faces and avoid angry ones, while their hearts respond more strongly to both fearful and angry expressions than to sad ones, suggesting that fear and anger carry distinctive urgency signals for the dogs. Cuaya was careful to note that photographs lack the smells, sounds, and body language that dogs experience in real life, and that not finding a neural distinction between sad and angry faces in photographs does not mean dogs cannot tell those emotions apart when they encounter them in person. Her practical summary was characteristically warm: our findings give us an extra excuse to smile at dogs in the park.

Source:https://www.earth.com/animals/mri-scans-show-dogs-can-tell-human-expressions-apart/