Dear Jonathan,
There’s no doubt that the relationship between humans and dogs is special. But does your best pupper understand everything you tell them?
I asked my friend Cassidy Cordon. She’s a veterinarian at Washington State University.
She told me that dogs understand lots of human words. But dogs also pay attention to their human’s tone of voice and body language to figure out what the human means.
Let say you teach your dog that “walk” means you’re going to take a stroll. Your dog friend might recognize the word “walk.” But they might also notice that you’re picking up their leash or putting on your shoes. They might pay attention to how excited your voice sounds—and whether that matches your tone when you taught them the word “walk.”
“If a different person delivers the word differently or if you say a happy thing in a different tone of voice, you may not get the same response,” Cordon said.
She told me we know a lot about this because scientists trained dogs to lie down inside MRI machines. Then they watched images of the dog’s brain while humans talked to them. They know that one side of a dog’s brain recognizes words. The other side recognizes tone.
When the word and the tone matched—like saying “good boy” in a happy voice—both sides of the dog’s brain were active. When the word and tone didn’t match—like saying “no” in a happy voice—the dog might understand the tone but not the word.
That’s how human brains process language, too.
We also know that most dogs can learn between 90 and 165 words. That’s about how many words most human toddlers know.
But there have been some exceptional dogs. The most famous might be Chaser. She was a border collie who learned more than 1,000 words. She could learn new words by inference. That’s using information you already know to figure out something you don’t know.
Let’s say someone added a new toy to Chaser’s toy pile and asked her to retrieve it by name. She could look at all those toys and eliminate the ones she already knew. Then she could figure out the new word must mean the unfamiliar toy.
That’s pretty impressive, but it’s still a lot fewer words than you probably know. The average 10-year-old human knows about 20,000 words—and adds another 20 words to their vocabulary every single day.
We also know that dogs seem to understand more when listening to a human they know. Maybe that’s because humans have been building close friendships with dogs for about 30,000 years.
Cordon told me that humans and dogs adapted and evolved together.
“We changed our behavior and trained ourselves as we trained them,” she said. “That’s why we can accomplish what we can with dogs now.”
It just goes to show that anything is paw-sible when you’re besties.
Sincerely,
Dr. Universe