When humans smell the perfume of someone they love, they can have an immediate and emotional reaction that isn't based in cognition. Dr. Gregory Berns who led the study in dogs' reactions to human scent, says dogs have the same reaction -- even when their owner wasn't present.
"It's one thing when you come home and your dog sees you and jumps on you and licks you and knows that good things are about to happen," Berns said.
"In our experiment, however, the scent donors were not physically present. That means the canine brain responses were being triggered by something distant in space and time. It shows that dogs' brains have these mental representations of us that persist when we're not there."
For the experiment, the dogs were presented with 5 scent samples while undergoing brain scans: one that came from the subject itself, one that came from a dog the subject had never met, one from a dog that lived in the subject's household, one from a human the dog had never met, and one from a human that lived in the subject's household.
The results showed that reactions to the scent of familiar humans were strongest, followed by reactions to the scent of familiar dogs.
"This suggested that not only did the dogs discriminate the familiar human scent from the others, they had a positive association with it." said Berns.
An interesting finding was that service dogs had the strongest reactions to their owner's scent compared to the other dogs.