There is a large amount of behavioral evidence which suggests that dogs are quite good at reading human emotions (click here, here, or here for examples). However a new study extends our knowledge about the way that dogs monitor the moods of people. It provides evidence that the brains of dogs and humans process the emotional tones of voices in the same way. This research was done by Attila Andics, Márta Gácsi, Tamás Faragó, Anna Kis, and Ádám Miklósi, who are researchers in Budapest, Hungary and their report appears in the journal Current Biology.
The starting point for this research can be traced back to 1999 when a group of Canadian researchers headed by Pascal Belin identified a part of the human brain that appears to be designed to recognize human voices. It is important to note that this so-called "voice area" doesn't process words or sentences, rather it decodes all of the non-linguistic aspects of the sound. This would include information about the identity of who is speaking, but it also includes the emotional tone of the sounds. Thus this area would analyze how the speaker was feeling. Is he angry, afraid, happy or sad?
In this recent study the researchers wanted to see if dogs have a region in their brains similar to that voice area found in people. They decided to use the same methodology used on human beings, namely scanning the brain using a type of MRI that measures brain activity and records which areas are active at any time. The idea was to compare the responses evoked by particular sounds in the brains of dogs and people. The researchers tested 11 dogs and compared their brain scans to those of 22 human volunteers. Even for a person, remaining still in an MRI scanner can be a strain, so needless to say a lot of training was required to teach the dogs to lie still for periods of up to eight minutes in the apparatus. I won't go into the details of how the researchers trained the dogs to do this except to say it involved heaps of treats, praise, love, and the opportunity to watch other dogs doing the same job and getting rewarded. In total there were 12 sessions of preparatory training followed by seven sessions with the dogs actually in the scanner room.
Once the dogs were trained, the researchers put earphones on each dog and then let them listen to three types of sounds. The first were environmental noises (car sounds, phone ringing, whistles etc.). The second involved dog vocal sounds such as other dogs barking, whining, growling and so forth. The third set of sounds were human voice sounds which did not involve words, thus the listener might hear laughter, a sad sigh, a groan and other emotion bearing sounds. In total each human and dog listened to 200 different sound samples.
It should not be a surprise to find that the brains of both dogs and humans responded most vigorously when they heard sounds made by their own species. However one surprise was that there was one region of the brain—the temporal pole which is in the very front portion of the temporal lobe (see the figure)—that was strongly activated when both dogs and people heard human voices.
Once we add emotions to the sounds the region of major activity in the brain shifts to the superior temporal gyrus (see the figure). Emotional sounds made by humans, such as laughter or crying tended to light up this area with activity. In the very same way emotionally charged dog sounds, such as whimpering or growling caused a similar reaction in the brains of both the human and the canine listeners in exactly the same region of the brain.
According to the lead researcher Attila Andics, "The location (of the activity) in the dog brain is very similar to where we found it in the human brain. The fact that we found these areas exist at all in the dog brain at all is a surprise—it is the first time we have seen this in a non-primate."
These results provide additional evidence that the minds of dogs are tuned to respond to the emotional state of both their own species and of humans. The fact that dogs respond so well to human emotion may be the results of our selective breeding of canines over the eons. Certainly any dogs that responded well to our emotional states would be preferred as companions. As a result of this they would be cared for in a better way than their emotionally less sensitive mates. Such dogs would also probably be bred more frequently in the hopes of producing offspring which are as sensitive to our human moods as their parents. In such a way, over time, the entire race of domesticated dogs might end up with brains that are genetically tuned to read the moods of people.
Although these results are fascinating, they do not necessarily say anything about the ability of dogs to recognize human speech. It certainly would be interesting to see how dogs respond to words rather than just sounds. There is something special about words, at least for humans. Emotional sounds such as laughter, groaning, or crying, could be interpreted as being very close to the kinds of calls and sounds that all animals make, and that might account for some of the findings, although not for the fact that both dogs and humans have the same specific part of the brain that lights up at the sound of the human voice and another that responds vigorously to emotional sounds. Such considerations have not escaped Dr. Andics who says that language and word sounds will be the focus of his next set of experiments.
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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