Kenneth Glad
Researchers are finding that animals living closely with people respond to facial cues in surprisingly specific ways. New imaging work shows that those responses are not identical across every negative expression.
Fear emerged as the clearest dividing line when scientists compared dogs’ brain responses to human faces displaying several emotions.
In research published in iScience, activity patterns associated with fearful faces could be distinguished from those linked to sadness and anger. The analysis did not produce the same separation between angry and sad faces.
That distinction matters because earlier research had already established that dogs are sensitive to human faces. The newer findings suggest their neural responses may be more detailed than a simple division between positive and negative expressions.
The result should not be taken as proof that dogs consciously identify fear, anger or sadness. The scans reveal differences in brain activity when certain images are shown, rather than demonstrating that dogs interpret those expressions exactly as people do.
What the scans revealed
The research used two groups of pet dogs. One part of the study involved eight animals shown happy and neutral faces, while another involved 12 dogs viewing happiness, anger, fear and sadness.
Happy faces produced stronger activity in a portion of the right temporal cortex extending into the caudate nucleus. Laura Cuaya of the University of Vienna highlighted that finding, writes People.
“The activity in the caudate nucleus is particularly interesting,” she said. “It suggests that happy human faces may have emotional significance for dogs.”
Researchers also proposed that fear and anger may command attention more quickly than sadness because they can carry greater immediate relevance. The finding involving fear, however, came from differences detected across whole-brain activity patterns rather than evidence that the dogs consciously labeled the emotion.
What the study cannot prove
The researchers used still photographs taken from databases in which people had already classified the displayed emotions. The experiment therefore tested whether dogs’ brains responded differently to those categories of images, not whether the animals understood the expressions in human terms.
There were other limitations. The sample was small, many participants were border collies, and photographs cannot reproduce the movement and changing expressions dogs encounter in daily interactions.
Despite those constraints, the study adds evidence that canine responses to human faces can vary within the broad category of negative expressions. Future work could further examine how dogs’ long association with people relates to their sensitivity to human social signals.
Sources: iScience, People
