A dog's brain is only one-tenth the size of a human's brain and they are often attributed with the intelligence equivalent to that of a two year old child. Although recently, through technology like a MRI machine, researchers are learning there is much more on a dog's mind than they expected. Researchers with several institutions wanted to see how a dog's brain responded to certain stimulus. They trained several dogs to sit still in an MRI machine for up to thirty minutes, then presented various sounds, scents, and experiences to the each dog, and then scanned how their brain's responded.
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| Volunteers pose with the brain scanner at the MR Research Center in Budapest. |
In a UK study, two researchers at Goldsmiths College in London, Deborah Custance and Jennifer Mayer, set out to determine if dogs are capable of empathy – an ability to truly understand emotion. They gathered a group of largely untrained pets, mostly mixed breeds and equally divided between males and females. Then they set up a situation with the dog’s owner and a stranger to the dog. The owner and the stranger would alternately talk, hum in an odd way, or cry. The researchers wanted to see how the dogs reacted. The dogs responded — 15 of the 18 in the study — by seeking out the person in distress, even if that person was the stranger. (1)
Here is a list of how a dog's brain reacts to humans through sight, smell, and hearing:
#1 Sound
A study shows dogs have a special ability to react to human speech and respond emotionally to sounds that humans make. Although canine breeding may have enhanced this ability, wolves are also quite vocal and sensitive to emotion so it may be why humans and canines made such a great team in the first place. It also confirms, to some, that both humans and canines had a common ancestor millions of years ago. Researches think this because we use similar brain mechanisms to process social information. They believe that sophisticated sound-processing and emotional sensitivity is a fundamental trait of all mammals that developed through a common ancestor 100 million years ago.
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| Anatomy of a human (above) and dog brain, with areas linked to vocal processing outlined. Image: Andics et al./Current Biology |
“What makes us really excited now is that we’ve discovered these voice areas in the dog brain,” said comparative ethologist Attila Andics of Hungary’s Eötvös Loránd University, lead author of the Feb. 20 Current Biology paper describing the experiments. “It’s not only dogs and humans. We probably share this function with many other mammals.”
Conducted in the laboratory of fellow Eötvös Loránd ethologist Ádám Miklósi, one of the world’s foremost researchers on canine intelligence and behavior, the study was inspired by a turn-of-the-millennium discovery of regions of the human brain attuned to human voices. Similar regions have since been described in monkeys, which last shared a common ancestor with humans 30 million years ago. (2)This part of the brain doesn't process words or sentences but rather it processes information packed into the subtle changes in sound with pitch and tone, identifying the speaker or detecting distress for example. This region, for both humans and dogs, is located in the back of the brain, near the ears. 11 dogs and 22 human volunteers were played the same 200 sounds and the researchers found that although both dogs and humans respond more strongly to sounds made by their corresponding species, dogs did process humans sounds and interpret them correctly.
“We do know there are voice areas in humans, areas that respond more strongly to human sounds that any other types of sounds,” Dr. Attila Andics, the lead author of the study, explained to BBC. “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 is a surprise — it is the first time we have seen this in a non-primate.”
“We know very well that dogs are very good at tuning into the feelings of their owners,” said Andics, “and we know a good dog owner can detect emotional changes in his dog – but we now begin to understand why this can be.” (3)Researchers at the Max Planck Institute for Evolutionary Anthropology in Leipzig studied two border collies that could learn human speech as quickly as a two year old child, Rico and Betsy. Rico's ability to learn at least two words a day displayed an innate set of principles in the key building blocks of language acquisition. The technique he uses for learning words is identical to that of humans. To find more examples, the scientists read all the letters from hundreds of people claiming that their dogs had Rico’s talent. They found Betsy, a border collie with a vocabulary of up to 300 words.
“Even our closest relatives, the great apes, can’t do what Betsy can do—hear a word only once or twice and know that the acoustic pattern stands for something,” said Juliane Kaminski, a cognitive psychologist who worked with Rico and is now studying Betsy. (4)
#2 Scent
A study proves your dog really does love you, researchers have found that a key space in the brain that processes positive emotion only lights up when the dog is presented with a familiar human's scent. These same regions fail to activate when exposed to other dogs - even familiar ones - according to researchers at Emory University in Georgia.
"It is tempting to conclude that (this) response represents something akin to a positive emotional response to the scent of a familiar human," writes the research team led by Gregory Berns. (5)
Their study, published in the Behavioural Processes, involved training a dozen dogs to remain motionless, while unsedated and unrestrained, in an MRI machine. A dog's sense of smell is 10,000 to 100,000 times greater than that of humans. Part of that is because the dog has 50 times more olfactory receptors than the human nose. A human nose has 6 million sensory receptors while a dog have 300 million sensory receptors or more. It is also attributable to the dog's brain. Proportionally, a dog's brain assigns 40 percent more space to analyzing smells than the human brain does. Researchers were able to observe the dog's olfactory bulb, which indicated the dog's sense of smell had been activated, and the caudate. Rich in dopamine receptors, the caudate sits between the brainstem and the cortex. In humans, the caudate plays a key role in the anticipation of things we enjoy, like food, love and money. Specific parts of the caudate stand out for their consistent activation to many things that humans enjoy. Caudate activation is so consistent that under the right circumstances, it can predict our preferences for food, music and even beauty. (6)
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| MRI scan of dog's caudate lighting up when given a reward signal. |
This same brain system exists in dogs and researchers believe they use it to process pleasurable experiences, functioning just as the human caudate would. Smells were presented to the dogs from the dog itself; a different dog who resided in the same household; an unfamiliar dog; a familiar human; and a human the dog had never met. The olfactory bulb was activated similarly with each scent presented, but the smell of the familiar human activated the caudate region far more noticeably. Even if the familiar human was not the primary caregiver and the dog was not accustomed to receiving treats from this person. This is proof that dogs have the ability to experience positive emotions, like love and attachment, and would mean that dogs have a level of sentience comparable to that of a human child. It puts away old notions that animals, including dogs, are like robots and experience no emotions. Surprisingly, it was a view that was popular among scientists and researchers up until quite recently.
#3 Sight
When humans study a new face their eyes fall to the left, observing the right side of the face first. This is because the right side of the human face expresses emotions much more clearly than the left side. This "left gaze bias" only occurs when we encounter faces and does not apply any other time, such as when inspecting animals or inanimate objects. Researchers at the University of Lincoln have now shown that dogs also display "left gaze bias", but only when looking at human faces. No other animal has been known to display this behavior before. A team led by Dr Kun Guo showed 17 dogs images of human, dog and monkey faces as well as inanimate objects. Film of the dogs' eye and head movement revealed a strong left gaze bias when the animals were presented with human faces. But this did not occur when they were shown other images, including those of dogs. (7)
"Guo suggests that over thousands of generations of association with humans, dogs may have evolved the left gaze bias as a way to gauge our emotions," New Scientist magazine reported.
"Recent studies show that the right side of our faces can express emotions more accurately and more intensely than the left, including anger. If true, then it makes sense for dogs - and humans - to inspect the right hand side of a face first."
This proves that dogs understand that human emotion is displayed on the face and because it benefits them to respond accordingly, they have developed a way of detecting our moods. Betsy, the border collie with a vocabulary of 300 words, also showed an amazing ability to identify pictures of objects. Despite the images of toys being two-dimensional, Betsy showed no inability to connect the two-dimensional object to it's three dimensional counterpart. The owner held up a picture of a fuzzy, rainbow-colored Frisbee and urged Betsy to find it. Betsy studied the photograph and her owner's face, then ran into the kitchen, where the Frisbee was placed among three other toys and photographs of each toy. Betsy brought either the Frisbee or the photograph of the Frisbee to her owner every time.
“It wouldn’t have been wrong if she’d just brought the photograph,” Kaminski said. “But I think Betsy can use a picture, without a name, to find an object. Still, it will take many more tests to prove this.”A team of researchers at the University of Helsinki conducted a study. They measured dogs’ eye movements when the dogs were exposed to facial images of familiar humans and dogs, compared to their responses to facial images from dogs and humans the canines had never met. The dogs spent more time looking at familiar faces than strange ones, but did look at images of other dogs longer than images of humans, regardless of their familiarity with the faces in the images. (8)
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| Betsy will retrieve an object after being shown just a picture of it. |
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