From Healthy Pets
By Dr. Karen Becker
- New study results suggest that dogs understand spoken words even better than we thought
- Researchers concluded that dogs recognize spoken words regardless of the speaker, and they do it instinctively
- The study proves that despite previous assumptions, this spontaneous ability is not uniquely human and that dogs share this linguistic talent
- Earlier research indicates that dogs hear not only what we say, but how we say it
- Similar to us, our dogs use the left hemisphere of their brains to process meaningful words, and the right hemisphere to process vocal tones
The ability to recognize specific word sounds (e.g., vowels) in human speech is assumed to be a uniquely human trait. After all, small differences in sound frequencies can completely change the meaning of a word, for example, “had”, “hid” and “who’d,” or “mat”, “mitt”, and “met.” The sound changes between these groups of words are so minor that word recognition software often misinterprets them.
In addition, the sound of words changes depending on the speaker — his or her age, body size, mouth shape, and other factors. For all these reasons, many researchers have held the opinion that instinctive recognition of word sounds is uniquely human, and that animals such as dogs would need training, at a minimum, to develop the skill.
However, if you’re a dog parent or spend time around dogs, you’ve probably seen for yourself that dogs can and do learn words from one person and recognize those words when they’re spoken by someone else. I’d venture to guess the vast majority of family dogs recognize the word “treat” no matter who says it!
Study: Dogs Understand Spoken Words Better Than We Thought
Recently, a team of U.K. researchers decided to see if dogs are able to recognize the same little sounds (called phonemes) that make up words, when the words are spoken by different people with varying accents and pronunciation.1
The researchers chose words that began with an “h” and ended with a “d” but had different vowels —such as “had”, “head”, “hid” and “hood” — and that would also have no meaning to the dogs. The words were recorded by 14 female and 13 male speakers of varying ages and different accents, none of whom were familiar to the dogs in the study.
Each dog sat with his or her owner near an audio speaker while a sequence of six recorded words played with six seconds of silence between each word. The dog’s responses were videotaped.
Psychology professor and neuropsychological researcher Stanley Coren, Ph.D., author of the best-selling book “The Intelligence of Dogs,” in an article for Psychology Today, describes a likely testing scenario:
“One experimental trial might have run this way. The dog to be tested is presented with a string of repetitions of the word ‘had’ through the speaker. Suppose that in this instance the word was spoken by a woman.
Typically, when the dog first hears this new word spoken by this female voice he would point his ears forward, or move toward the speaker, or flick his eyes in the direction that the sound was coming from, all of which are signs of attention and engagement.
“However, as other women with different accents repeat the word ‘had’ the dog loses interest indicating that he knows that they are all saying the same thing. On the other hand, when a female speaker in the sequence says a new word, one with a different vowel, like ‘hid’, the dog now perks up again, indicating that he noticed the difference. But when the next woman’s voice returns to saying ‘had’ his attention will again flag.”2
After evaluating the videotaped sessions, the researchers concluded that dogs recognize spoken words regardless of the speaker, and they do it instinctively.
“These results are significant because they confirm two important aspects of speech recognition in dogs,” Coren writes. “First, they can distinguish between subtle changes in vowel sounds that identify particular words. Second, dogs isolate the important word sounds from all of the changes in sound quality associated with different speakers.”
Lead study author Dr. Holly Root-Gutteridge, a postdoctoral researcher with the Mammal Vocal Communication and Cognition Research Group in the School of Psychology at the University of Sussex made this observation in an interview with Sci-News:
“The ability to recognize words as the same when spoken by different people is critical to speech, as otherwise people wouldn’t be able to recognize words as the same when spoken by different people.
This research shows that, despite previous assumptions, this spontaneous ability is not uniquely human and that dogs share this linguistic talent, suggesting that speech perception may not be as special to humans as we previously thought.”3
Dogs’ Brains Work Similar to Ours to Process What We Say
In 2016, researchers in Budapest published a study that looked at how dogs’ brains process human speech.4 They came to the conclusion that our canine friends listen not only to what we say, but how we say it.
The scientists discovered that when we praise our dogs, the reward centers in their brains perk up if the words we use match our tone of voice. These findings suggest the ability to process words evolved much earlier than was originally thought and may not be unique to humans.
According to Phys.org, the study shows “… that if an environment is rich in speech, as is the case of family dogs, word meaning representations can arise in the brain, even in a non-primate mammal that is not able to speak.”5
For the study, the researchers recruited 13 family dogs — primarily Border Collies and Golden Retrievers — who excelled at lying completely still in an fMRI scanner, facilitating analysis of their brain activity. The dogs were volunteer study participants, were never restrained inside the scanner and could leave at any time.
The researchers recorded a trainer’s voice saying certain phrases with varying types of intonation. In the recordings, the trainer praised the dogs using Hungarian words and phrases that in English translate to “good boy,” “super,” and “well done.”
The words were spoken in both an upbeat tone and a neutral tone. The trainer also used neutral words like “however,” and “nevertheless” that meant nothing to the dogs.
While the recording played, the researchers studied the scans for regions of the dogs’ brains that were differentiating between the praise and meaningless words, as well as praise and neutral tones of voice. They observed that the dogs used the left hemisphere to process meaningful (but not meaningless) words, and the right hemisphere to process vocal tones.
Per Phys.org, “This was the same auditory brain region that this group of researchers previously found in dogs for processing emotional non-speech sounds from both dogs and humans, suggesting that intonation processing mechanisms are not specific to speech.”
Lead researcher Attila Andics of Eötvös Loránd University in Budapest explains:
“During speech processing, there is a well-known distribution of labor in the human brain. It is mainly the left hemisphere’s job to process word meaning, and the right hemisphere’s job to process intonation.
The human brain not only separately analyzes what we say and how we say it, but also integrates the two types of information, to arrive at a unified meaning. Our findings suggest that dogs can also do all that, and they use very similar brain mechanisms.”6
Processing Words Doesn’t Necessarily Mean Understanding Them
“One important thing is that we don’t claim that dogs understand everything we say, of course,” Andics told HuffPost in an email.7
There can be a difference between a dog processing words for their familiarity and actually understanding the words as we intend. As study co-author Adam Miklosi, head of the Family Dog Project told Scientific American magazine:
“‘Understanding’ is a tricky word. Studies using brain imaging technology cannot firmly say that the activation of a specific brain area indicates ‘understanding.’
“For sure, dogs in this study reacted to the meaningful words, that is, to those words that their owners often use when they want to attract the dog’s attention or provide a positive feedback for the dog. So in this sense our dogs recognized these words as familiar and probably meaning something good.”8
An important result of the study is that it demonstrates the left hemisphere of dogs’ brains processes meaningful words separate from the vocal tone. This suggests your dog may understand that “good dog” is praise regardless of the tone of voice you use when you say it, because he recognizes those words as meaningful vs. meaningless.
“We think that intonation is important,” says Miklosi. “Owners should learn how to praise a dog, and then use the same expression in similar way. Consistency in praising and in general in communication with the dog is important.”
The researchers suspect they would have similar results in studies of other domestic animals like cats and horses, as long as the animals had lived among humans. They hope this study and subsequent research can be used to enhance communication and cooperation between dogs and humans.