GEOFF BENNETT: And how about a moment of uplift, yes?

All right, a viral online phenomenon claims to have further opened the door to human canine communication, prerecorded buttons that allowed dogs to seemingly talk with their humans.

AMNA NAWAZ: But are all these button enthusiasts barking up the wrong tree?

William Brangham, along with his pup Macy doggedly pursue the truth.

ACTOR: You didn't know dogs could talk?

WILLIAM BRANGHAM: It's been a fascination of ours for generations.

ACTOR: Speak.

ACTOR: Hi there.

WILLIAM BRANGHAM: Getting man's best friend to talk.

ACTOR: I like to play ball.

I like purple bird in the window.

WILLIAM BRANGHAM: And for good reason.

Tens of millions of us live with and love the dogs in our lives, including me.

And we want to know what they're thinking.

FEDERICO ROSSANO, University of California, San Diego: We love dogs and we love bonding with them.

But I think while we know that they understand us pretty well, many of us still struggle making sense of what they want.

WILLIAM BRANGHAM: Federico Rossano studies animal communication.

He's a cognitive scientist at the University of California, San Diego.

FEDERICO ROSSANO: When you see your dog scratching at the door, you might know they want to get out.

But you don't know why they want to get out.

WILLIAM BRANGHAM: But our furry friends have remained frustratingly mum, that is, until this Australian cattle dog named Stella stepped onto a button and into online fame.

Stella's dog mom is Christina Hunger.

She's a speech pathologist who got the idea for these dog buttons after working with nonverbal children, where she'd often use a tablet to assist them in communicating.

CHRISTINA HUNGER, Speech-Language Pathologist: At the same time, I brought a puppy home who was just bursting with communication, which led me to the question, if dogs can understand words we say to them, why can't they say words back?

What if they had a different way to talk, similar to kids who use devices?

WILLIAM BRANGHAM: The idea behind these buttons is that you record onto the button a word or a phrase that you use all the time with your dog.

For my dog Macy, that could be: "Go for a walk" or "Want a treat."

And then, every time I do that action in the course of a day, I press the button.

And with enough repetition, the hope is that someday Macy would push that button to communicate back with me.

Hunger spent weeks demonstrating her buttons for Stella with no results.

She was about to call it quits when Stella seemed to get it.

CHRISTINA HUNGER: She just started looking at the button and looking up at me, or she would actually swat and miss it.

You're so close, Stella.

That's when I knew that there was some potential here and I kept going with teaching.

And then a week later, she said her first word outside.

AUTOMATED VOICE: Outside.

CHRISTINA HUNGER: Let's go outside.

WILLIAM BRANGHAM: Hunger's blog and her social media videos have drawn millions of viewers, including cognitive scientist Rossano, who was skeptical.

AUTOMATED VOICE: Outside.

FEDERICO ROSSANO: I was like, well, there's one dog doing it and that's great.

But we know that there's a history of trying to communicate with animals, and that history was a little, let's say, complicated.

WILLIAM BRANGHAM: That history includes a horse named Clever Hans, who wowed audiences in the early 1900s for seemingly being able to do math.

Turns out Hans was just picking up subtle cues from his handler.

But the buttons and the people and dogs who used them kept growing in popularity.

AUTOMATED VOICE: "I dog, we friend."

ALEXIS DEVINE, Dog Owner: I dog, we friend, yes.

I had no business teaching my dog how to talk.

I wasn't a speech language pathologist or a dog trainer or a scientist.

But what the heck?

WILLIAM BRANGHAM: Alexis Devine and her sheepadoodle, Bunny, were inspired by Christina Hunger.

She started posting Bunny's progress online.

ALEXIS DEVINE: No.

WILLIAM BRANGHAM: She says, after six years of steady work, Bunny now knows over 100 words and, she claims, uses them in novel ways.

ALEXIS DEVINE: I think one of the most powerful moments was when she had a foxtail embedded in the webbing between her paws.

So she went over to her board and she pressed "mad ouch."

And I said, where is your ouch?

And she pressed "Stranger paw."

So she had used stranger in a way that I had never modeled it, stranger being something foreign, foreign object.

WILLIAM BRANGHAM: Videos like this went crazy online.

Over eight million people follow Bunny and Devine on TikTok.

She's now written a book, sells her own brand of button boards, and has inspired millions more to try them.

AUTOMATED VOICE: Treats.

MAN: You want treats?

WILLIAM BRANGHAM: Cats, otters and even pot-bellied pigs are now experimenting with the buttons.

WOMAN: You have to say thank you.

AUTOMATED VOICE: Why?

WILLIAM BRANGHAM: This sudden growth in button users gave Rossano an opportunity, a large-scale study of button communication focusing on dogs.

FEDERICO ROSSANO: Our plan of having maybe 100, 200 participants turned into more than 10,000 participants from 47 countries and is the largest animal communication study ever attempted.

WILLIAM BRANGHAM: Over several months, Rossano and his team collected and analyzed millions of button pushes and hundreds of hours of video of dogs using them.

They also conducted controlled behavioral studies.

A first finding from their research published in August concludes that dogs can comprehend specific words and can offer contextually appropriate responses.

But, Rossano says, that's still a far cry from proving they can use actual humanlike language.

FEDERICO ROSSANO: I don't see the evidence that the dogs are really understanding language in anything close to the way that you and I are as we talk together here.

WILLIAM BRANGHAM: Clive Wynne studies dog psychology.

He directs the Canine Science Collaboratory at Arizona State University.

He says dogs using those buttons is fine, but don't get carried away with what is really going on.

CLIVE WYNNE, Arizona State University: I don't think that inside the mind of a dog there is a human mind desperate to get out.

I think inside a dog's head there's a dog's mind, and a dog's mind has its own ways of communicating.

WILLIAM BRANGHAM: Yes, when my dog wants to communicate that she's hungry, she does two things.

She nudges my elbow with her snout or she stands by her food bowl.

And it's crystal clear what she wants, that she's hungry.

CLIVE WYNNE: So that's a beautiful example, William, of how you have learned your dog's language.

Your dog has a way of communicating with you about their desire for food.

And you would not gain anything by training your dog to press buttons that would say the exact same thing.

WILLIAM BRANGHAM: For Christina Hunger, who now sells her own line of button boards, there's simply a way of enriching and deepening our relationship to these animals that have lived alongside us for tens of thousands of years.

CHRISTINA HUNGER: Buttons will never replace body language.

There's another tool that adds on top of and gives a lot more clarification for both the dog and the human.

WILLIAM BRANGHAM: Macy, want a treat?

AUTOMATED VOICE: Want a treat?

WILLIAM BRANGHAM: For the "PBS News Hour," from the new frontier in human-canine communication...

I'm going to push a button.

...

I'm William Brangham.

AUTOMATED VOICE: Want a treat?

GEOFF BENNETT: How many of those buttons are you going to put in your house for your new dog?

AMNA NAWAZ: All of them.

I feel like my dog needs two buttons, treat now.

Treat now.

Yogi's covered.

(LAUGHTER) GEOFF BENNETT: All right.