Chaser: Unlocking the Genius of the Dog Who Knows a Thousand Words

Chaser: Unlocking the Genius of the Dog Who Knows a Thousand Words

Chaser: Unlocking the Genius of the Dog Who Knows a Thousand Words

Chaser: Unlocking the Genius of the Dog Who Knows a Thousand Words


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NEW YORK TIMES BESTSELLER. The amazing story of a very smart Border collie who redefined animal intelligence. A joyous explanation of behavior, learning, and perception—any pet owner, parent, teacher, or psychologist will be enriched by this book.

Chaser has fascinated dog lovers and scientists alike. Her story reveals the potential for extending dialogue with dogs well beyond "fetch."

When retired psychology professor John Pilley first got his new Border collie puppy, Chaser, he wanted to explore the boundaries of language learning and communication between humans and man's best friend. Exhibiting intelligence previously thought impossible in dogs, Chaser soon learned the names of more than a thousand toys and sentences with multiple elements of grammar.

Chaser's accomplishments are revolutionizing the way we think about the intelligence of animals. John and Chaser's inspiring journey demonstrates the power of learning through play and opens our eyes to the boundless potential in the animals we love.

"The most scientifically important dog in over a century." — Brian Hare, founder of the Duke Canine Cognition Center

Product Details

ISBN-13: 9780544334595
Publisher: HarperCollins Publishers
Publication date: 09/23/2014
Pages: 288
Sales rank: 223,973
Product dimensions: 5.20(w) x 7.90(h) x 0.90(d)

About the Author

JOHN W. PILLEY was an emeritus professor of psychology at Wofford College. He began working with Chaser in 2004 and has published the findings from their work in the journal Behavioural Processes.

Hilary Hinzmann is a freelance editor and writer based in New York City.

Read an Excerpt


The Dog Who Knows a Thousand Words

The twenty or so nine-year-old boys and girls squirmed and murmured in their seats as Chaser walked into their fourth grade classroom at Public School 31 in Brooklyn.

“She’s here!”

“She looks bigger on TV.”

“She’s so cute!”

The small tables the children usually sat at were pushed to the back and sides of the room, and their chairs were lined up in two curving, staggered rows, so they all had a good view of the space that had been cleared at the front of the classroom.

I let Chaser off the leash, and she went straight to my grandson, Aidan, who was sitting at one end of the first row with a giant smile plastered on his face.

Aidan had been begging us to bring Chaser to visit his class. He had told his teacher, Mrs. Tapper, about our visit to New York for several national television appearances, and most of the class had watched Chaser on Nova scienceNow a few days before demonstrating her unprecedented language skills. And here we were, about to give the class a demonstration in person.

After greeting Aidan, Chaser moved on to the other children, looking up at each one expectantly and wagging her tail. As Aidan’s classmates leaned down to stroke Chaser’s side, her tail wagged harder and her tongue lolled out of her mouth in an ecstatic canine grin.

Chaser is not an imposing dog physically. She’s normal Border collie size, about 20 inches tall at the shoulder and about 40 pounds. Her thick fluffy coat is mostly white with splotches of grey and flecks of black, except for large patches of black on the left side of her head, both sides of her torso, and her hind legs. Although she has plenty of spirit, overall she has a soft temperament. I often tell people, “She’s a lover, not a fighter.”

All the same, a few children were a little shy about touching Chaser. Any dog can be intimidating for people who aren’t used to them. Chaser has lots of experience with children, however. She knows that they’re the best possible candidates for her favorite activity, play. She wiggled and squirmed and wagged her tail appealingly in front of the shyer kids, and soon even the most reluctant children were grinning right back at her.

It was time to begin. We only had an hour and there was a lot to show. The principal, Mrs. Scarlato, went and stood in the back of the classroom with her camera, and Mrs. Tapper introduced my wife, Sally, our daughter (and Aidan’s mom) Debbie, and me to the class. Then I called Chaser to me and she lay down at my feet.

“I’m Dr. Pilley,” I told the children, “and I’m a scientist. Can anyone tell me what scientists do?”

One boy’s hand shot up, and I pointed to him. “Scientists invent things,” he said. Another offered, “They look at stars and rocks and stuff like that.” And a girl said, “They study plants and animals, too.”

I asked, “Why do scientists study things like rocks and stars and oceans and plants and animals? What are they looking for?”

Another girl said, “They want to discover things.”

“A-ha, that’s it! That’s what we scientists are after, discovery! Chaser and I have been trying to discover how much human language she can learn.” I see Chaser as a co-investigator and research assistant rather than as an experimental subject. Just as she’s a part of our family, she’s also the other half of my research team. “I understand you’ve heard that Chaser knows more than a thousand words.”

Over the previous few weeks there had been headlines around the world about Chaser. It all began just before Christmas, with the e-publication of a peer-reviewed scientific article on my research with Chaser. I’d written it with the help of Alliston Reid, a former student of mine at Wofford College in Spartanburg, South Carolina, where he had succeeded me as a professor of psychology.

The article, published first online and later in print by the British journal Behavioural Processes, reported that Chaser had learned and retained the proper noun names of 1022 objects over a period of three years. She had also learned to understand and distinguish the separate meanings of proper noun names and commands, and had learned at least three common nouns, or words that represent whole categories of things. Furthermore, she could learn a new word by exclusion, meaning that she could infer the relationship between a name she had never heard before and an object she had never seen before, by picking the new object out of a group of objects whose names she already knew. These are abilities that are normally seen in children when they are learning language as toddlers, and there is fierce debate among scientists as to whether animals can really do the same things.

On December 8, 2010, the day the article was published online, I received a phone call from a journalist for the British magazine The New Scientist. Two weeks later, the online edition of The New Scientist ran a story with the headline, “Border collie takes record for biggest vocabulary.” Our phone started ringing off the hook and my email inbox began filling up with messages from print, online, and broadcast media. Over the week from Christmas to New Year the Chaser story “went viral,” as Debbie’s husband, Jay, explained it to me.

In more than 46 languages, the headlines ran the gamut from silly to serious. The National Examiner put Chaser on the cover next to Brad Pitt and Charlie Sheen. Most of the media attention centered on Chaser’s knowing over a thousand words, which MSNBC noted is more than most toddlers know. There was also lots of speculation about whether Chaser was “the world’s smartest dog.”

“So far as it’s been documented,” I told the class, “Chaser knows more words than any other dog. In fact, she knows more words than any other animal except humans. We’re going to demonstrate Chaser’s learning of words for you in a minute. But first I want to show you some learning that she shares with a lot of Border collies.”

I opened the plastic bin we’d brought with us and showed the children what was inside: twenty of Chaser’s toys, mostly stuffed animals and dolls, but also balls and Frisbees. Each one had a name written on it in permanent ink, like “Bamboozel,” “Frat Rat,” “Bear,” “Croc,” “Sponge Bob,” “ABC,” “Prancer,” and “Santa Claus.” Among the rest of her toys at home there was more than one teddy bear, but the other bears had unique names with no repeats. That made it possible for Chaser to keep them straight in her head.

I put one of the toys, a foam Frisbee with “Flipflopper” written on it, down on the floor about eight feet away from Chaser. She had her head down as if she had no interest in what I was doing. Only experience told me that she was “giving an eye to the sheep and an ear to the farmer,” as Border collie trainers say. Flipflopper was one of Chaser’s flock of named toys, one of the 1022 surrogate sheep she has acquired in her language training. Any activity to do with Flipflopper was important to her.

With her ears down and her eyes half closed, Chaser looked like she was in a trance state, as more than one journalist has described her in these moments. But she had her legs and feet drawn under her evenly on both sides. That was the one tell-tale sign that she was ready to spring into action, as soon as I spoke the words that told her what I wanted her to do.

“Chaser, go out,” I said, using the words that sheep farmers have traditionally used to start their dogs towards some sheep.
Chaser instantly got to her feet and walked towards the foam Frisbee.

“There,” I said, and Chaser stopped still.

“Chaser, come by,” I said, and she walked around the Frisbee clockwise.

“There,” I said, and she stopped again.

“Chaser, way to me,” I said, and she walked around the Frisbee counterclockwise.

The children were murmuring with interest and inching their chairs forward.

“There,” I said, and Chaser stopped still again.

“Chaser, drop.” She dropped flat on her belly. Some of the kids started giggling.

“Chaser, crawl,” I said, and she began to crawl toward the Frisbee. More giggling from the kids.

“Chaser, one, two, three, take!” I said, my special signal to release her to rush to the toy and take it in her mouth. She began shaking the Frisbee with delight, triggering applause from the kids, and I encouraged her in that for ten or fifteen seconds. Then I said, “Chaser, bring Flipflopper. Drop Flipflopper in the bin.”

When she’d dropped Flipflopper in the bin I told the class, “That’s Chaser’s reward. She gets to play with the toy. On a sheep farm, a Border collie’s reward would be moving the sheep around. Border collies have a strong herding instinct, and that’s what they like to do best. Now for Chaser, each of these toys represents a sheep that she gets to herd in different ways. Like I said, she knows more than a thousand objects by name. The next closest dog, a Border collie in Germany named Rico, knew a couple of hundred words, and Rico was part of my inspiration for the scientific study Chaser and I have done. Now we’ll demonstrate Chaser’s word learning for you.”

I had written the names of four of the toys in the bin on note cards, and I gave the cards to two of the boys and two of the girls.

“Don’t call out what’s on your card yet,” I told them. “First I’ll ask Chaser to find some toys by name. And then I’ll ask the four of you to ask Chaser to find the toys whose names are written on the cards.”

I dumped all the toys out of the bin in a jumble on the floor several feet away from Chaser. She again had her head down as if she had no interest in what I was doing. I came back over to her and said, “Chaser, find Sponge Bob.”

Chaser sprang to her feet and trotted over to the toys. She looked over the toys for a moment, and then spotted Sponge Bob at the bottom of the pile and pulled him out. That really excited the kids.

“Shake Sponge Bob, Chaser,” I said, to give her a moment’s play as reward, and then had her bring Sponge Bob over and drop him in the bin.

I asked Chaser to find and bring over nine more toys, calling for each by its unique name. With ten toys still left on the floor, but spread out a bit now by Chaser’s nosing and pawing among them, I asked each of the four students in turn to ask Chaser to find the toys written on the note cards.

“Chaser, find Santa Claus,” the first child said.

“Chaser, find Bamboozel,” the second child said.

“Chaser, find Mickey Mouse,” the third child said.

“Chaser, find Croc,” the fourth child said.

One by one Chaser found the toys. After she’d had a chance to play with a toy for a few moments, which always delighted her, I asked her to deposit it in the bin.

Each time Chaser did something one of their classmates asked for, the class got more and more excited. It was a shame we couldn’t give them all a chance to work with her. But in the time we had left, I wanted to show the kids two more aspects of Chaser’s language learning.

Earlier I had asked the kids how many of them had a dog at home, and about half did. When I do classroom demonstrations in places where most people live in houses with backyards, practically every kid will raise their hand.

Now I said, “Those of you who have dogs, when you tell your dog, ‘It’s time to go for a walk,’ does your dog understand that each of those words has a separate meaning?”

They all said, “No.”

“What word do you think your dog does know?”

The kids gave various answers, but the consensus was that their dogs all knew the word “walk.”

“Well, ‘It’s time to go for a walk’ is a pretty long sentence. How about something simpler? If you throw a ball and say, ‘Fetch ball,’ does your dog understand that those two words have separate meanings?”

This was a tough question, but the kids finally decided that their dogs really only understand the “fetch” part.

“Many scientists think that’s all a dog can ever learn. They say that dogs don’t really understand that different words have separate meanings; they just learn to associate your words and gestures with certain actions you want them to make, like ‘sit,’ ‘stay,’ or ‘fetch.’ Chaser and I did another experiment to test exactly that.”

I took three of Chaser’s toys, Bear, Croc, and Prancer, and put them on the floor.

“Okay, class, we have three toys, and we can use three different commands. We can ask Chaser to nose a toy, paw it, or take it, which means take it in her mouth. And we can mix the three commands up with the three objects in any way we like. Let me show you.”

In succession, I asked Chaser to nose, paw, and take different toys, and then I picked a couple of students to do the same.

“What do you think, class?” I asked. “If we can use different commands with different toys, does this show that Chaser understands that a word for an action means one thing and a word for an object means another thing?”


“I agree with you,” I said. I didn’t add that I was waiting to see if any scientists in the field of animal learning would find fault with my experiment and cast doubt on its results. As it happened, no one did. In fact, in the three years since the Behavioural Processes paper was published, no one has rebutted any of its specific findings, although the controversy about animal learning continues unabated. Meanwhile, Chaser’s learning has also continued, reaching remarkable new heights that include adding many common nouns to her vocabulary, understanding sentences with three elements of grammar, and progress in imitation learning.

“I wish Chaser and I could spend longer with you,” I told the class, “but we’re running out of time, and there’s one more thing we really want to show you. Chaser can learn the name of a new object even though she’s never seen the object or heard its name before, and she can do it in one try. All the toys I brought with me are things Chaser knows the name of, so we need a new object. But we don’t want Chaser to see it yet. Aidan, why don’t you take Chaser behind Mrs. Tapper’s desk? That way we can be sure she can’t see anything.”

Aidan grinned at his classmates, looked over at Mrs. Tapper to make sure she had no objection, and took Chaser behind the desk and crouched down with her. For good measure he put his hands over Chaser’s eyes, and I thanked him for doing that.

Then I asked the class, “Does anyone have an object we can use?”

Lots of kids raised their hands. But a girl in the second row caught my eye by waving a bright red plastic change purse.

“That looks good,” I said, taking the purse from her outstretched hand. “What are we going to call it?”

“Purse!” several kids said.

“We could do that, but Chaser’s heard the word purse many times, and she probably knows that
Aidan’s mother and grandmother and other people have purses. So she might already have an association for the word ‘purse’ in her mind. We want a name that will be completely new to Chaser. It could be anything, it could be just a silly sound, like ‘Woosh.’ Should we call this ‘Woosh’?”

This sparked smiles and laughs. “Yeah, let’s call it ‘Woosh,’” the kids agreed.

I said, “We’ll put down some objects that Chaser already knows the names of, and then we’ll add this new one. She doesn’t know what it looks like, and until just now she’s never heard the special name we’re giving it.

“Before we see if Chaser can find the new object when we ask for it by its special name, let’s ask Chaser to find some familiar objects. She might come over here and take the new object just because it is new and she’s curious about it. We all like to get new things to play with, don’t we?”

I didn’t tell the children that a well-known animal learning researcher had criticized a study of word learning by the Border collie Rico, precisely for not establishing whether the dog had “a baseline preference for novelty” when it came to learning the name of a new object. This was one of a number of criticisms by prominent researchers of the Rico study, which was published around the same time Sally and I got Chaser as a little puppy. I had carefully designed my own experiments, such as asking Chaser to find some familiar objects first, in the hope of avoiding such criticism.

At this point, I asked Aidan to go back to his seat and I called Chaser over to me. Then I said, “Chaser, find Mongrel.” Chaser found Mongrel among the toys. And then I asked her to find other familiar toys by the names she’d learned for them. She found them all without a glitch, ignoring the unfamiliar object and demonstrating that she had no baseline preference for novelty. After each trial with a familiar toy, we put it back in the pile and jumbled all the toys up again.

Finally I said, “Chaser, find Woosh. Find Woosh.”

Chaser went over to the toys and looked them over carefully. She pawed them a bit, and then bent down and picked up the red plastic coin purse.

“Yes! Good girl, Chaser! Good girl! Chaser, bring Woosh. Bring Woosh.”

She brought the red purse over to me and dropped it in the bin.

The kids loved that, and they gave Chaser their biggest cheers. She responded with body wiggles and tail wags, ears up, eyes wide open, tongue lolling out of her mouth—all signs of how pleased she was to win the kids’ attention and affection. Then I said it was unfortunately time for us to leave and suggested they come to the front of the room and have their picture taken with Chaser. Chaos erupted, and they crowded so tightly around Chaser that she couldn’t be seen. She didn’t mind. She loved being petted and stroked by the children. But the chaos had to end, and Mrs. Tapper and Mrs. Scarlato good humoredly restored order and arranged the children around Chaser for a photograph.

My last words to the class were to remind them that play was Chaser’s reward. I told them that they should always reward their dogs for good behavior by playing with them and petting and praising them. We all learn better and faster when learning is fun.

A couple of days later, before Sally and I drove home to South Carolina with Chaser, Aidan came home from school with giant thank you cards that he and his classmates had each drawn of Chaser and signed. One little boy put himself in the picture with Chaser, giving himself a big red heart for a body and big stars for eyes. It was such an eloquent way of saying that he loved Chaser and she was a star in his eyes. A little girl drew a smiling Chaser with her toys, giving her a gold “Chaser” name tag on a pink collar that matches the pink of the insides of her ears. It was really touching to have all the children’s drawings.

Throughout the classroom demonstration, Chaser had been in her element. Finding objects, herding them, learning new objects and names, interacting with the children, in all these things Chaser was expressing her intensely social nature, a characteristic that all domestic dogs share in different ways, and her strong Border collie instincts and drives. Her unprecedented language learning rests on these two factors and on the relationship that Sally and I have built with her around them.

Together the three of us have gone on a journey of discovery we could never have anticipated. I had been retired for nine years when Chaser came into our family and reawakened my passion for discovery—really, reawakened me as a person as well as a scientist. But Chaser was not my first Border collie, and not the first dog to be my co-investigator and research assistant. Twenty years before Chaser, there was Yasha.

Table of Contents

1. The Dog Who Knows a Thousand Words 1
2. Good-bye 11
3. Christmas in June 26
4. Let the Puppy Be a Puppy 36
5. “You’ve Got to Name Her Chaser!” 52
6. Chaser Learns What Not To Chase 63
7. Listening to the Farmer 73
8. Learning by Playing 89
9. Herding Words 108
10. Herding Sheep 119
11. Advanced Lessons 129
12. Getting Published 138
13. Going Viral 153
14. Chaser Takes a Bow 167
15. Chaser Goes to Washington 193
16. Expanding the Conversation 209

Epilogue: Unleashing Chaser’s Genius 229
Appendix 231
Acknowledgments 237
Index 238

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