Dogs Hear Word Meanings and Emotions Differently
Like people, dogs have a part of the brain that is tuned to understand language.
Posted Dec 03, 2014
To test what was going on in dogs' brains when people speak these researchers brought 250 pet dogs, of many different breeds, into their laboratory. The dogs were placed in a room with speakers on either side of their heads.
Ratcliffe explained, "The input from each ear is mainly transmitted to the opposite hemisphere of the brain. If one hemisphere is more specialized in processing certain information in the sound, then that information is perceived as coming from the opposite ear." She goes on to suggest that if a dog turns its head to the right while it's listening to a sound then we can conclude that its left hemisphere played a strong role in processing that sound, while I had turned to the left would suggest that the right hemisphere of the brain is more involved in analyzing the sound.
The really clever part of this research has to do with the sounds that the dogs had to listen to during testing. The phrase which was used was "Come on, then!" Spoken by the dog's owner in the typical happy tone that we use when we are encouraging our dogs to come to us. However this sound clip could be modified in a number of ways. For our purposes there were two critical modifications of the initial speech sample. One sound clip had the emotion electronically stripped out of the voice sample, however the words could still be understood. Other sound sample involved the same phrase with the words garbled so that they could not be understood, however this sound sample left the intonation and emotional content of the speech intact.
The data was rather straightforward. The researchers found that dogs turned their heads to the right when they heard words without any emotional content in the voice sample, suggesting that the left hemisphere was processing that speech. In contrast, the dogs turned their heads to the left when they heard the meaningless voice sounds which still contained emotional content, suggesting that the right hemisphere was processing that bit of speech. Of course there were also some control conditions, such as samples of pink noise (a kind of static), however the dogs did show any bias toward turning their heads to either side when they heard this sounds.
"Although we cannot say how much or in what way dogs understand information in speech from our study," Ratcliffe said, "we can say that dogs react to both verbal and speaker-related information and that these components appear to be processed in different areas of the dog's brain.”
Her co-author, David Reby, goes on to emphasize the important conclusion to be drawn from this research. "This is particularly interesting because our results suggest that the processing of speech components in the dog's brain is divided between the two hemispheres in a way that is actually very similar to the way it is separated in the human brain."
In other words the argument that dogs are unlikely to be able to interpret complex language information because their brains are not organized in a manner which has a region specialized for interpreting word meanings no longer seems to be tenable. Dogs, like humans have brains that have areas that are wired to pick out and process word meanings. Once again research seems to suggest that the minds of dogs are less different from the minds of people than was previously believed.
Stanley Coren is the author of many books including: The Wisdom of Dogs; Do Dogs Dream? Born to Bark; The Modern Dog; Why Do Dogs Have Wet Noses? The Pawprints of History; How Dogs Think; How To Speak Dog; Why We Love the Dogs We Do; What Do Dogs Know? The Intelligence of Dogs; Why Does My Dog Act That Way? Understanding Dogs for Dummies; Sleep Thieves; The Left-hander Syndrome
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* Data from: Victoria F. Ratcliffe and David Reby, Orienting Asymmetries in Dogs’ Responses to Different Communicatory Components of Human Speech, Current Biology (2014), http://dx.doi.org/10.1016/j.cub.2014.10.030