Dog owners often say that their pets understand far more than they let on. A muttered complaint or an offhand mention of a favorite toy can suddenly trigger a knowing look, a wagging tail, or a sprint toward the door.
Now, a new peer-reviewed study suggests that, for a small but remarkable group of dogs, this ability to understand human vocabulary may be more true than previously believed.
In research published in Science, cognitive scientists say that some dogs can learn the names of new objects simply by overhearing conversations between humans—without being directly addressed, trained, or prompted.
Significantly, the learning pattern closely mirrors how human toddlers acquire language at around 18 months of age, a developmental milestone long thought to be uniquely human.
The findings challenge traditional assumptions about the limits of animal cognition and suggest that some of the social and cognitive mechanisms underlying early language learning may not be exclusive to human beings. Instead, they may rest on more general social skills that can, under the right conditions, emerge in nonhuman animals that live closely alongside people.
“A small group of Gifted Word Learner dogs, which possess an extensive vocabulary of object labels, can learn new labels by overhearing their owners’ interactions,” researchers write. “These results suggest that Gifted Word Learner dogs possess sociocognitive skills functionally parallel to those of 18-month-old children.”
While most dogs can reliably learn commands like “sit” or “stay,” researchers say a rare subset of dogs known as “Gifted Word Learners” demonstrate an unusual ability to recognize dozens—and in some cases hundreds—of specific object names without any formal training.
Led by cognitive scientist and animal trainer Dr. Shany Dror, researchers set out to test whether these dogs could extend this ability even further by learning new words simply by passively listening in on human conversations.
In human infants, this ability typically emerges around 18 months of age, when children begin to acquire vocabulary not only through direct instruction but also by overhearing adults talking about objects in their surroundings.
In developmental psychology, this type of learning is known as learning from “overheard speech.” It requires a complex mix of social skills, including tracking where others are looking, understanding communicative intent, and recognizing that words spoken between two people can refer to objects in the shared environment.
“Demonstrating similar learning processes in nonhuman species would indicate that the social-cognitive skills supporting this process are not exclusively human but may have evolved, or can develop, in other species, offering valuable insights into the origins of language-related cognition,” researchers write.
Dogs, the researchers argue, are a particularly promising species in which to look for such abilities. Over thousands of years of domestication, dogs have evolved alongside humans, becoming highly attuned to human gestures, attention, and communication.
Previous studies have shown that dogs can follow human pointing, respond to gaze direction, and even recognize familiar action commands embedded in speech not directed at them. What remained unclear was whether dogs could do the same with object names.
To investigate this idea, researchers conducted a series of carefully controlled experiments with ten Gifted Word Learner dogs—most of them border collies, a breedlong regarded for its exceptional problem-solving ability and intelligence.
In the first phase of testing, owners introduced two new toys using a naturalistic routine that involved briefly naming the toy, playing with it, and then allowing the dog to explore it freely. When tested days later, the dogs reliably retrieved the correct toy when asked by name, confirming that they had learned the labels.
In a second experiment, the same dogs were present in the room but ignored while their owner and another family member discussed the toy. The owner named the object within simple sentences and passed it back and forth, using enthusiastic gestures and gaze shifts—but never addressing the dog directly.
Despite being ignored during the labeling phase, most of the dogs later demonstrated that they had learned the new object names anyway. When asked to fetch a specific toy, they chose correctly at rates far exceeding chance, performing just as well as they had when the labels were taught directly to them.
Statistical analyses showed that the dogs performed just as well when they overheard a conversation as when they were directly addressed. Even on the very first retrieval attempt—before they could learn anything during the test itself—the dogs chose correctly, indicating that learning had already taken place during the overheard interaction.
To rule out the possibility that this ability was common to all dogs, the researchers ran the same overhearing experiment with ten typical family dogs that did not have a known vocabulary of object names.
Although some of the typical dogs appeared to favor new toys during testing, a closer statistical analysis revealed that this behavior was driven by novelty preference rather than true word learning. In the end, none of the typical dogs displayed reliable evidence that they had formed object–label associations by overhearing human speech.
According to researchers, the contrast highlights just how unusual the Gifted Word Learner dogs are, and that the ability to learn from overheard speech cannot be generalized to dogs as a species. Instead, it appears to reflect a rare combination of individual traits, developmental history, and social environment that allows certain dogs to exploit human communicative cues in extraordinary ways.
In a final set of experiments, the researchers asked whether Gifted Word Learner dogs could learn object labels when the object itself was not visible at the moment the word was spoken.
In this “discontinuity” condition, owners briefly showed the toy, hid it in a container, and only then spoke its name while directing their gaze toward the hidden object.
Remarkably, most of the Gifted Word Learner dogs still formed accurate word–object associations, retrieving the correct toy days later—and again two weeks afterward, suggesting the memories were stable.
This ability mirrors findings in human children, who can also learn words when an object is temporarily out of view, relying on social cues and an understanding of communicative intent rather than simple timing.
In some dogs, the results suggest that learning does not depend solely on hearing a word and seeing an object at the same time. Instead, the animals appear to use a combination of contextual and social information to infer meaning.
Researchers are careful to stress that their findings do not suggest that dogs understand language in the human sense, nor that they possess grammar or syntax.
However, the results do suggest that some of the building blocks that support language learning—especially the ability to learn from others by observation and inference—may be more broadly distributed across species than previously assumed. In dogs, these abilities may have been amplified by thousands of years of domestication and close coevolution with humans.
Dogs evolved in the human ecological niche, the authors note, undergoing selection pressures that favored sensitivity to human gestures, attention, and communicative intent. Over time, that may have produced animals uniquely equipped to exploit human social information, even when humans are not deliberately teaching them.
The findings also raise the intriguing question of why only a small number of dogs display Gifted Word Learner abilities. Researchers emphasize that this ability is extremely rare and caution that it should not be assumed to reflect a general evolutionary adaptation in dogs.
“It is still unclear how Gifted dogs developed their initial ability to learn object labels,” researchers write. “As the phenomenon is very uncommon, we consider it likely that this ability results from idiosyncratic factors.”
Whether similar sociocognitive mechanisms exist in other species, and under what conditions they emerge, remains an open area for future research.
Nevertheless, the findings add to a growing body of evidence suggesting that the cognitive gap between humans and other social species may be narrower—and more nuanced—than once believed.
For dog owners, the takeaway may be simpler but no less intriguing. When your dog seems to be listening in on your conversations, it might not just be your imagination—at least not for a gifted few.
Tim McMillan is a retired law enforcement executive, investigative reporter and co-founder of The Debrief. His writing typically focuses on defense, national security, the Intelligence Community and topics related to psychology. You can follow Tim on Twitter: @LtTimMcMillan. Tim can be reached by email: tim@thedebrief.org or through encrypted email: LtTimMcMillan@protonmail.com