Dogs can understand the meaning of nouns

Dogs understand what certain words stand for, according to researchers who monitored the brain activity of willing pooches while they were shown balls, slippers, leashes and other highlights of the domestic canine world.

The finding suggests that the dog brain can reach beyond commands such as “sit” and “fetch”, and the frenzy-inducing “walkies”, to grasp the essence of nouns, or at least those that refer to items the animals care about.

“I think the capacity is there in all dogs,” said Marianna Boros, who helped arrange the experiments at Eötvös Loránd University in Hungary. “This changes our understanding of language evolution and our sense of what is uniquely human.”

Scientists have long been fascinated by whether dogs can truly learn the meanings of words and have built up some evidence to back the suspicion. A survey in 2022 found that dog owners believed their furry companions responded to between 15 and 215 words.

More direct evidence for canine cognitive prowess came in 2011 when psychologists in South Carolina reported that after three years of intensive training, a border collie called Chaser had learned the names of more than 1,000 objects, including 800 cloth toys, 116 balls and 26 Frisbees.

However, studies have said little about what is happening in the canine brain when it processes words. To delve into the mystery, Boros and her colleagues invited 18 dog owners to bring their pets to the laboratory along with five objects the animals knew well. These included balls, slippers, Frisbees, rubber toys, leads and other items.

At the lab, the owners were instructed to say words for objects before showing their dog either the correct item or a different one. For example, an owner might say “Look, here’s the ball”, but hold up a Frisbee instead. The experiments were repeated multiple times with matching and non-matching objects.

During the tests, researchers monitored the dogs’ brain activity through non-invasive electroencephalography, or EEG. The traces revealed different patterns of activity when the objects matched or clashed with the words their owner said. The difference in the traces was more pronounced for words that owners believed their dogs knew best.

Similar blips in EEG recordings were seen when humans performed the tests and were interpreted as people understanding a word well enough to form a mental representation that was either confirmed or confounded by the object they were subsequently shown.

Writing in Current Biology, the scientists say the results “provide the first neural evidence for object word knowledge in a non-human animal”.

Boros emphasised she was not claiming dogs understood words as well as humans. It will take further work to understand, for example, whether dogs can generalise in the way humans learn to as infants, and grasp that the word “ball” need not refer to one specific, heavily chewed spongy sphere.

The study raises the question of why, if dogs understand certain nouns, more of them don’t show it. One possibility is that a dog knows what a word refers to but is not bothered about acting on it. “My dog only cares about his ball,” said Boros. “If I bring him another toy, he doesn’t care about it at all.”

Dr Holly Root-Gutteridge, a postdoctoral researcher at the University of Lincoln who was not involved in the study, called the work “fascinating”.

“It’s particularly interesting because I think it’s unlikely this started during domestication, so it may be widespread throughout mammals,” she said. “That’s highly exciting in itself as it shines new light on language evolution.

“It might be that the dogs don’t really care enough about the game of ‘fetch this particular thing’ to play along with the way we’ve been training and testing them so far. Your dog may understand what you’re saying but choose not to act.”