“Squirrel!” Scientists chase mystery of how dogs process words
If you holler “Squirrel!” and your dog jumps up all exited and runs to the window, does he actually picture a squirrel in his mind?
A new study found that dogs can tell the difference between words they’ve heard before and words that are new to them. At the very least, it suggests that dogs have a basic neurological understanding of the words they’ve been taught to associate with objects.
The study, published this month in the journal Frontiers in Neuroscience and conducted by researchers at Emory University in Atlanta, Georgia, is one of the first to use brain imaging to investigate how dogs process language.
“Many dog owners think that their dogs know what some words mean, but there really isn’t much scientific evidence to support that,” says Ashley Prichard, MS, a PhD candidate in Emory’s Department of Psychology and first author of the study. “We wanted to get data from the dogs themselves—not just owner reports.”
But before they could scan the dogs’ brains to get that data, the researchers had to teach them to differentiate between two toys based on their respective names.
Twelve dogs of varying breeds were trained for months by their owners to retrieve two different toys, based on the name of the toy. To make it as easy as possible on the dogs, researchers chose a soft toy and a toy of a different texture; for example, a golden retriever-Labrador retriever mix named Eddie was trained on a stuffed monkey named Monkey, and a squeaky rubber pig dubbed Piggy.
Once the dogs were trained, it was time for the functional magnetic resonance imaging scanner.
During one experiment, the dogs laid in the scanner while their owners stood in front of the dogs at the opening of the machine and said the names of the dogs’ toys at set intervals, then showed the matching toys while the researchers recorded the results.
In Eddie’s case, he heard his owner say the words “piggy” or “monkey” before holding up the corresponding toy.
As a control, the owners then spoke made-up words, such as “bobbu” and “bodmick,” and held up new objects the dogs had not been trained on, like a hat or a doll.
The results showed greater activation in auditory regions of the brain to the made-up words compared to the trained words. That didn’t surprise the researchers.
“We expected to see that dogs neurally discriminate between words that they know and words that they don’t,” Prichard says. What did surprise them: The dogs’ neural reaction was the opposite of what happens in humans, who typically show a greater neural reaction to words they know than words they don’t.
The researchers hypothesize that the dogs may show greater neural activation to the made-up words because they sense their owners want them to understand what they’re saying, and the dogs are trying to do so.
“We know that dogs have the capacity to process at least some aspects of human language since they can learn to follow verbal commands,” says Gregory Berns, PhD, MD, a professor of psychology at Emory and senior author of the study. “Previous research, however, suggests dogs may rely on many other cues to follow a verbal command, such as gaze, gestures, and even emotional expressions from their owners.”
Berns says the new study is significant because the findings suggest that dogs can understand human speech alone.
Photo Credit: © iStock/Jennifer McCallum