It's clear that people can interact with dogs. Throw a ball and say a dog "bring" and the dog retrieves the ball. But do dogs understand the word "bring" or do they just know that you threw a ball and made a sound? They could also be focused on some other word entirely — the tone of your voice, or the direction of your gaze. Fortunately, scientists have looked into this. A current study in Frontiers in Neuroscience is interested in exactly this question. Can dogs recognize words? "Knowing" is a big, difficult thought — difficult to examine in the field of one study, and hard to define for a dog. Think of all the things that go on in your mind when you hear a word you "understand": you identify what it means; if it has multiple meanings, you figure out which one makes the most sense in context; you understand its tone and level of formality; and so on. Do we need dogs to do all of that? Just some? It's a clear question, but the researchers decided that one fundamental, cross-species element of understanding was "the discrimination of words from non-words." In other words, dogs should be able to differentiate familiar commands from nonsense sounds. They decided to take a new approach to test dog understanding, though. Historically, researchers have measured dogs' knowing through action. In other words, if a dog recognizes the term "bring," they'll bring a ball. This mixes up an understanding with obedience, however, and muddies the results.
So in this research, the researchers relied not on action, but on fMRI brain scans. While dogs were in the scanners, their owners said a variety of simple and gibberish words to them. However, none of the familiar words were action-oriented — instead, they were the names of two various dog toys (ex: "Piggy" and "Monkey"). Would the dogs present different levels of brain activity when they heard "Piggy" than when they heard a gibberish word? Short answer: yes! Here's the long answer: This study of 12 dogs started with training. Each dog spent between two and six months memorizing the names of two different toys. First, the dogs' owners just frequently named the objects. They'd play bring or tug-of-war with their dogs using, say, Monkey, and repeatedly say "Monkey!" as they played to reinforce the object's name in the dog's mind. Here's the long answer: This study of 12 dogs started with training. Each dog spent between two and six months memorizing the names of two different toys. First, the dogs' owners just frequently named the objects. They'd play fetch or tug-of-war with their dogs using, say, Monkey, and frequently say "Monkey!" as they played to strengthen the object's name in the dog's brain.
The fMRI scan was the last stage. While dogs held still in the tubular machines, their owners addressed them from outside, saying a mix of known words like "Monkey" and "Piggy" and mechanically generated non-words like "su," in various combinations. It turned out that the dogs did reach the base principles for understanding — their brains reacted differently to familiar words than they did to unknown words. Interestingly, the dogs' brains responded differently than human brains; their brain activity spiked when they heard unfamiliar words, whereas human brain activity spikes when we hear familiar words. It's unclear why dogs react differently to the different, or how deep their understanding of our words goes. But this study at least suggests that our speech is more than background chatter to dogs — they can recognize one word from another.
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