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Dogs, humans use similar parts of brain to interpret numerical quantities

By
Brooks Hays
The Dog Project, founded by Emory neuroscientist Gregory Berns, uses canines as a model for studying a variety of evolutionary questions. Photo by Emory University
The Dog Project, founded by Emory neuroscientist Gregory Berns, uses canines as a model for studying a variety of evolutionary questions. Photo by Emory University

Dec. 18 (UPI) -- Dogs don't get numerical symbolism, they don't know that the number four is greater than the number two, but they can appreciate numerical quantities. Now, new research suggests canines and humans process numerical quantities using similar parts of the brain.

Most research into numerical cognition involves humans and non-human primates. Scientists at Emory University wanted to better understand how numerical cognition plays out inside the brains of other mammals.

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"When non-primate species have been studied, the experiments typically involved extensive training in order to get the animals to perform a task designed to assess their numerical abilities," Stella Lourenco, an associate professor of psychology at Emory, told UPI in an email. "As a result, we know very little about what numerical capacities non-primates exhibit spontaneously, in the absence of training."

Lourenco and her colleagues used functional magnetic resonance imaging, or fMRI, to study activity in dogs' brains as they watched different numbers of dots flash on a screen. The images revealed heightened activity in the dogs' parietotemporal cortex.

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"In humans, the area of the brain most commonly associated with processing of numerosity is the intraparietal sulcus, a sub region of parietal cortex," Lourenco said.

The research showed dogs use similar parts of the brain to process numerical quantities. However, the neural processes weren't exactly the same.

"We did observe more variability in the particular location of activation in each dog, compared to the variability commonly observed across adult participants, however, as we also observed significant activation in temporal cortex," Lourenco said. "We believe this may in part reflect anatomical differences, as the dogs in the present study were of varying breed."

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The differences also may reflect the fact that humans and dogs utilize a diversity of neural patterns to process numbers.

The new research, published Wednesday in the journal Biology Letters, suggests the ability to interpret numerical quantities is present throughout the animal kingdom.

"Although some behavioral research had suggested that dogs can discriminate stimuli on the basis of numerosity, research to date has been mixed," Lourenco said. "Other work had suggested dogs cannot discriminate on the basis of numerosity when other visual features, such as total area, were incongruent."

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Previous studies examining dogs and their choice between food bowls showed dogs prefer food with a greater volume of food, even if there are a greater number of treats in the other bowl.

"It may be the case that dogs can tell that one bowl has five treats and the other has 10 treats, but if the five treats constitutes a greater volume of food, they select that bowl because, when considering food, volume is more relevant. Because of these difficulties, we wanted to study dogs' numerical abilities outside the context of food choice."

The new research offers the strongest evidence yet that dogs and humans share a neural mechanism for numerosity dating back at least 80 million years, and suggest most animals enjoy some base level of numerical understanding.

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