Thanks to behavioral science and the fMRI, we now know that dogs are able to understand the actual words their owners use — not just voice intonation, as previously thought.

Until a recent study was published in Science magazine, most dog owners thought that no matter what words they used, they could convince their dog that it was being praised if they used an affectionate tone. But this new canine brain study indicates that dog owners have likely been underestimating their dogs’ comprehension skills. 

The dog brain study from Eötvös Loránd University in Budapest revealed that dogs do not rely exclusively on tone when they listen to human speech. Many dogs are able to recognize the meaning of frequently used words.

Behavioral scientists used functional Magnetic Resonance Imaging (fMRI) to examine patterns of brain activity in 13 specially trained dogs as they listened to their trainer speaking either words of praise or neutral words. 

The two types of commonly used Hungarian phrases were selected. Importantly, the dogs heard the two common phrases delivered in both a praising and neutral tone on multiple occasions. According to the study, “This was absolutely critical for disentangling any distinct effects that word content and intonation might have on the canine brain. Indeed, the setup led to several interesting discoveries, including fascinating similarities in the ways speech is processed in the dog and human brain.”

fMRI scans revealed that words of praise triggered particularly strong activations in the dogs’ left hemispheres. It did not matter whether they were delivered as praise or in an entirely neutral tone. Researchers believe that dog brains are capable of extracting the arbitrary symbolic content that humans assign to words, and have learned their special significance.

Researchers also found that reading intonation in human speech was found in the opposite hemisphere, the right side of the dog’s brain – just as it is in human brains. Right-side brain regions, which normally process auditory information, responded to neutral and praising tones of delivery with different levels of activation regardless of actual word content.

“This anatomical contrast of word meaning and intonation in the canine brain is strikingly similar to what we know about the brains of humans,” remarked Leanne O’Neil of INDY Neurofeedback. “We’ve known since the turn of the 19th century that humans with damage to part of the left hemisphere could be fluent in speech but lack comprehension. They also had difficulty understanding the meaning of others’ speech. More recently, researchers have discovered that those with certain types of right hemisphere damage can understand the meaning of words, but struggle to interpret people’s emotional states — or humor — which are usually expressed by tone. So it’s interesting to discover that the two hemispheres of dog brains appear to be similarly specialized for interpreting communications.” 

It turns out that dogs use tone to assess the possibility of hearing some rewarding content, but integrate both sources of information to ultimately decide whether they are indeed being praised. This effect doesn’t seem to be too different from what happens in the human brain when we assess whether or not something we are taking in is pleasant. We do this for example, when we evaluate how much we like a particular piece of music.

The similarities between how canine and human brains interpret speech by integrating word meaning and intonation probably dates back to the dawn of canine domestication. 

In the process of selecting dogs with characteristics that made them better companions for us, we inevitably also selected for brains that process communications in a similar way to ours. 

After all, similarly tuned brains are probably better suited for connecting with each other. Another reason dogs are our best friends.