Image Courtesy of Dr. Laura Cuaya.
Just about everyone with a pet has experienced the phenomenon of talking to an animal without any expectation of an intelligible response. Even though our pets don’t understand exactly what we’re saying, many pet owners claim that they have grown closer to their pets by talking to them. Have you ever wondered just how much your pet takes away from these interactions? Dr. Laura Cuaya and her fellow researchers at Eötvös Loránd University’s Department of Ethology have made great strides in understanding how dogs process what they hear.
Cuaya was motivated to study speech perception in dogs because of her personal experience moving from Mexico to Hungary with her dog, Kun-kun. “Before, I had only talked to him in Spanish. So I was wondering whether Kun-kun noticed that people in Budapest spoke a different language, Hungarian,” Cuaya said.
Cuaya noted that dogs are a particularly interesting species to study because their evolutionary history starts off completely separated from humans and later switches to taking place alongside humans with the advent of dog domestication. “With dogs, we have a wonderful opportunity to study the evolution of speech perception. Although humans and dogs are evolutionarily distant, due to the domestication process, both species have been sharing an environment for thousands of years. Dogs needed to adapt their social minds to a human environment. Understanding humans became important for them,” Cuaya said. Although there are different biological mechanisms and neuronal pathways in dog and human brains, both species have developed unique manners of completing the same task––recognizing human speech patterns––over the course of their evolutionary history.
Cuaya conducted a study on eighteen family dogs (including her own dog, Kun-kun) to determine how the canine brain detects speech and represents language. Her research focused on determining how dogs react to four main types of sound: natural speech in a familiar language, natural speech in an unfamiliar language, scrambled speech in a familiar language, and scrambled speech in an unfamiliar language. To observe which parts of the dogs’ brains were active in response to different types of speech, Cuaya used functional magnetic resonance imaging (fMRI), a scan that measures small changes in blood flow to map brain activity. Multivoxel pattern analysis (MVPA), a technique that correlates neural activity patterns to different areas of the brain where stimuli are processed, was used to analyze the fMRI results.
One of the biggest challenges Cuaya faced was making sure the dogs stayed still in the fMRI machine. For fMRI scans to be usable, there can only be up to three millimeters of movement while the dogs are laying in the scanners. Dog trainers were brought in to teach the dogs to stay still for the duration of the scan, and dog owners stayed nearby throughout the entire scans to keep the dogs comfortable and relaxed. The dogs were free to leave at any time.
Cuaya found that the primary auditory cortex responsible for processing simple sounds in dog brains showed different responses to scrambled and normal speech. Furthermore, different neural activity patterns were seen in the secondary auditory cortex, the part of the brain that processes more complex noises, when dogs listened to the language they were most often exposed to compared to a language they hadn’t heard before. Even though we don’t teach our dogs the language we speak, they become familiar with it because of the evolutionary advantage associated with it. When we speak, our dogs are actually picking up on the rhythms in our voice and the sounds of our words. Dogs with the ability to recognize subtle cues in their owners’ language were more easily domesticated, and with domestication came the benefit of food and shelter.
Cuaya offered an analogy to help us better understand dog speech perception by comparing it to an experience many of us can relate to when traveling. “Maybe you have experienced this feeling as a tourist in a new place. You think to yourself, I don’t know what language that is, but I know it’s not English,” Cuaya explained. Dogs experience the same thing when hearing people speak in a language they aren’t used to.
The next time you go to vent about your day to your pets, maybe you’ll think twice about just how much of your speech they’re really picking up on. They might just be paying more attention than you think, and you have our mutualistic evolution with dogs to thank for that.