New analysis suggests dogs develop a basic neural image and definition of learned words.
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| On of the study's canine participants, Eddie, poses with two of the toys used in the study, "monkey" and "piggy." Eddie showed the ability to fetch the toy named by his owner. Photo by Gregory Berns/Emory |
Dogs respond to verbal cues, but the degree with which dogs understand and process words remains a mystery.
To better understand how the canine brain comprehends different words, scientists imaged the brains of dogs responding to verbal cues. The analysis suggests dogs develop a basic neural image and definition of learned words.
"Many dog owners think that their dogs know what some words mean, but there really isn't much scientific evidence to support that," Ashley Prichard, a doctoral candidate in the psychology department at Emory University, said in a news release. "We wanted to get data from the dogs themselves -- not just owner reports."
Before scientists imaged the brains of dogs, they had owners teach each canine study participant a pair of words. The owners trained their dogs to learn the names of two toys.
Dogs were considered trained when they consistently returned with the toy named by their owner, leaving the unmentioned toy behind. Owners used one soft and one hard toy so dogs could easily differentiate between the two.
While inside an MRI machine, the dogs watched as their owners showed the canines each toy and said the name associated with each -- "monkey" and "piggy," for example. Owners also verbalized nonsensical names.
The brain images showed an increase in neural activity when owners spoke gibberish like "bobbu" and "bodmick."
Humans tend to experience an uptick in neural activity when reacting to words they already know. The latest findings -- published Monday in the journal Frontiers in Neuroscience -- prove dogs experience an opposite effect.
"We expected to see that dogs neurally discriminate between words that they know and words that they don't," Prichard said. "What's surprising is that the result is opposite to that of research on humans -- people typically show greater neural activation for known words than novel words."
It's likely dogs pay closer attention to new words because they are intent on learning how to please their owners.
In half of the canine participants, the activity increase was located in the parietotemporal cortex. Scientists think the parietotemporal cortex is similar to the angular gyrus, the portion of the human brain responsible for processing lexical differences.
Other dogs experienced neural activity increases in other parts of the brain, including the left temporal cortex, amygdala, caudate nucleus and thalamus. Different breeds may process words differently.
"Dogs may have varying capacity and motivation for learning and understanding human words, but they appear to have a neural representation for the meaning of words they have been taught, beyond just a low-level Pavlovian response," said Emory neuroscientist Gregory Berns.
While the latest study suggests dogs are capable of processing words, previous studies have shown dogs pay closer attention to visual cues and scent.
"When people want to teach their dog a trick, they often use a verbal command because that's what we humans prefer," Prichard said. "From the dog's perspective, however, a visual command might be more effective, helping the dog learn the trick faster."
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