Dogs have a cerebral representation of the meaning of the words they have been taught, beyond a simple Pavlovian response, shows an American study.
Researcher Ashley Prichard and her colleagues at Emory University are interested in the brain mechanisms that dogs use to differentiate words.
When a master pronounces the words “cat” or “squirrel” to his dog, the dog gets excited and sometimes runs to the door or window.
But what exactly does Rex understand? Is it “attention, something is happening”? Or does it represent the mental image of a small rodent with a bushy tail?
Many dog owners think that their dogs know what certain words mean, but there was not really much scientific evidence to support it.
“We wanted to get answers from the dogs themselves, not just the owners’ comments,” says the researcher.
Did you know?
Scientists knew that dogs have the ability to deal with at least some aspects of human language, since they can learn to follow verbal commands. However, previous studies show that dogs can rely on many other clues to follow a verbal order, such as the look, gestures and even emotional expressions of their master.
Researchers used magnetic resonance imaging to look at the brain mechanisms that dogs use when they process the words they have been taught to associate with objects.
The owners of twelve dogs trained them to learn how to recover two different objects, depending on the name of the objects.
The pair of objects in each dog consisted of a soft texture object, like a stuffed animal, and another of a different texture, like rubber, to facilitate the distinction.
The training consisted of asking the dogs to pick up one of the objects and reward it with food or words of encouragement. Training was considered complete when a dog showed that he could distinguish between the two objects by systematically picking the one requested by the owner when presenting the two objects.
Then the dogs were lying in a scanner with the two objects in front of them while their masters stood directly in front of them. The masters then named the names of the toys at fixed intervals, then showed the dogs the corresponding toys.
For example, Eddie, a golden retriever labrador, heard his owner say the words “Piggy” or “Monkey” and then saw his owner hold the matching toy. As a control, the owner then uttered gibberish words, such as “bobbu” and “bodmick,” and then he showed new objects like a hat or a doll.
The results of this work suggest that Fido has at least a rudimentary neural representation of the meaning of the words he has been taught, and differentiates those he has already heard from those he does not know.
In addition, these results show greater activation in the auditory regions of the canine brain to new words versus learned words.
We expected dogs to distinguish between words they know and those they do not know. What is surprising is that this result is opposite to that of humans who generally show greater neuronal activation for known words than for new words.
Half of the dogs that participated in the experiment showed increased activation of new words in their parotemporal cortex, a region of the brain that researchers think is analogous to the angular gyrus in humans, where lexical differences are treated.
The other half of the dogs, however, showed increased activity at the new words in other areas of the brain, including other parts of the left and amygdala temporal cortex, the caudate nucleus and the thalamus.
The limits of the study
These differences may be related to the diversity of breeds and sizes of dogs, as well as to possible variations in their cognitive abilities.
Mapping the cognitive processes of the canine brain should therefore take into consideration the variety of shapes and sizes of the brain of dogs from one breed to another. What has not been done in the present work.
However, it seems clear that dogs have a neuronal representation of the meaning of the words they have been taught, beyond a simple Pavlovian response.
The classic conditioning thought by Ivan Pavlov at the beginning of the 20th century is a key concept of the theory of behaviorism.
In this theory, conditioning is a process by which an animal or human associates a programmed response (eg, salivating), which is normally triggered by a sense stimulus (food), to an unconditioned stimulus, c. that is, a neutral stimulus that normally triggers no response (the sound of a bell).
In his famous experiment, Mr. Pavlov rang a bell every time he served food to a dog. After a while, he rang the bell without feeding the dog, but the dog still salivated.
Words, but also gestures
The results of this research do not mean that spoken words are the most effective way for an owner to communicate with a dog.
In fact, other studies conducted by this team have shown that the neural reward system of dogs is more suited to visual and olfactory cues than to verbal cues.
“When people want to teach their dogs a trick, they often use a verbal command, because that’s what we humans prefer,” says Prichard. “From a dog’s point of view, however, a visual order could be more effective, helping him learn the trick faster. ”
The details of this work are published in Frontiers in Neuroscience.
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