New research indicates that dog brains can distinguish between different types of unhappy human faces. While previous studies showed dogs could differentiate some human facial expressions, it was unclear if they could tell apart various negative or positive expressions.
Dr. Laura Cuaya from the University of Vienna, a co-author of the study, stated this is the first demonstration that the dog brain can distinguish between emotions of the same valence. The research, published in the journal iScience, involved pet dogs undergoing MRI scans.
In one experiment, eight dogs showed increased brain activity in areas associated with visual, social, and reward processing when presented with happy faces compared to neutral ones. A second experiment with 12 dogs revealed that while happy faces could be distinguished from negative expressions, distinguishing between different unhappy faces was more complex.
However, by analysing activity across the whole dog brain, researchers found it was possible to distinguish between sad and fearful faces, and angry and fearful faces, but not between angry and sad faces. The authors suggested that dogs might require additional information, such as body language, to differentiate between anger and sadness.