A 2018 study from Emory Health Sciences by both Dr. Berns and Dr. Prichard focuses on the brain mechanisms dogs use to differentiate between words. According to Dr. Ashley Prichard, dogs have at least a basic neural representation of meaning for words they have been taught, and are able to differentiate from words that they have heard before, to those they have not.
In this study, the researchers wanted to explore the brain mechanisms dogs use to differentiate between words, or what may resemble a word to dogs.
"Many dog owners think that their dogs know what some words mean, but there really isn't much scientific evidence to support that. We wanted to get data from the dogs themselves -- not just owner reports,” says Ashley Prichard, a PhD candidate in Emory's Department of Psychology and the first author of the study.
“We know that dogs have the capacity to process at least some aspects of human language since they can learn to follow verbal commands," adds Emory neuroscientist Gregory Berns, founder of theDog Project, 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."
The most recent research published inFrontiers in Neuroscience discusses how brain imaging on dogs was used to see how dogs process words that they have been taught to associate with objects.
This study concluded that dogs have a basic neural representation of meaning for words that they have been taught and that they do differentiate between words that they have heard before to those that they have not heard. Dr. Berns explains that“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."
Using prior research from the Dog Project where dogs were trained to voluntarily enter an MRI scanner and remain motionless, Dr. Berns and his team better understood dogs’ neural response to an expected reward.
They also were able to identify specialized areas in the dog brain that allowed for dogs to process faces, showed olfactory responses to the dog and human smells, and were able to link prefrontal function to inhibitory control.
In the new study, the researchers used 12 dogs that were of different breeds. These dogs had been trained for a few months and had been taught to retrieve two different objects. These objects had names. One object was a stuffed toy and had a soft texture, and the other object was a rubber toy that felt different from the stuffed toy.
During training, the dogs were taught to fetch a specific object and were rewarded with food or praise. The training ended when the dog showed that he understood the difference between both objects.
During one experiment, the owner stood in front of the dog at the opening of the MR1 scanner and called out the toy names at set intervals. He also showed the dog the matching toys throughout the experiment. In the study, a Lab mix called Eddy heard the words “piggy” or “Monkey” when his trainer held up the toys.
After that, the owner spoke gibberish and then showed the dog new objects like a hat or doll. This one experiment concluded that there was greater activation in the auditory regions of the brain to new pseudo words compared to trained words.
Pritchard adds that"We expected to see that dogs neurally discriminate between words that they know and words that they don't. What's surprising is that the result is opposite to that of research on humans -- people typically show greater neural activation for known words than novel words."
In addition, the researchers hypothesized that dogs would show more neural activation when a new word was heard, because they felt that their owners wanted them to understand the new word, and they’re trying to understand them. "Dogs ultimately want to please their owners, and perhaps also receive praise or food," explains Berns.
During the study half of the dogs demonstrated an increased activation for new words in their parietotemporal cortex. This is an area of the brain that the researchers believe is similar to theangular gyrus in humans. The remainder of the dogs in the study surprisingly displayed heightened activity to new words in other brain regions which included the left temporal cortex and amygdala, caudate nucleus, and the thalamus.