Chaser_Unlocking the Genius of the Dog Who Knows a Thousand Words

by John W. Pilley

  Holding up the doll and pointing to it, I said, “Chaser! This is Santa Claus.”

  Saying “Pop-Pop hide Santa Claus,” I lowered the doll to the floor in plain view. Chaser’s gaze never left it, and I trusted that she was giving me her ear and a glance of her eye.

  I dropped the doll on the floor and said, “Chaser, find Santa Claus,” as she darted forward to pick it up in her mouth.

  “Good dog!” I told her. She looked up at me triumphantly, tail wagging, ears pricked up, and eyes bright and wide, eager to find out what was next.

  Stepping back a few feet I said, “To Pop-Pop, to Pop-Pop. Here,” beckoning her to me with outstretched arms. She came to me and let me take the doll from her mouth, as I again said, “Good dog!”

  Tossing the doll to her in a high arc, I said, “Chaser! Catch Santa Claus. Catch Santa Claus.” She reared up on her hind legs to catch the doll, and as her front feet hit the ground again her tail went up and wagged back and forth with excitement and pleasure. “Good dog, good girl!” I said, positively reinforcing her.

  “To Pop-Pop. Here,” I said. She brought me Santa Claus, and her tail wagged faster at hearing another enthusiastic “Good dog!”

  Finally I tossed Santa Claus into the middle of the living room and put Chaser through the herding behaviors: “Chaser, come by. Come by Santa Claus. Whoa. Way to me, way to me. There, there. Drop. Drop behind Santa Claus. Chaser, crawl to Santa Claus. There. Chaser, one, two, three, take Santa Claus! Good dog!”

  After this herding play with as many repetitions of the name Santa Claus and as much positive reinforcement as possible, we began all over. To keep the game interesting I progressively hid Santa Claus so that the doll was harder and harder to find. In each word training session, consisting of a brief trial at finding Santa Claus and a few minutes of play with it, I said the name twenty to forty times. Over the course of the day’s training sessions, we went through this exercise with Santa Claus at least twenty times.

  Over the next few days we continued to play this game with Santa Claus. We also played the game with other objects that were already familiar to Chaser. The excitement of finding the object, whether it was hidden in plain view or in the other room, put a grin on both our faces and got Chaser’s tail wagging with pleasure. After a brief moment to celebrate that victory, I rewarded Chaser with play with the object for three to five minutes. Depending on the object, the play might involve a little tug-of-war, chasing her as she scampered away with it, throwing it for her to catch or fetch, and most of all herding games. All the while, I repeatedly said the name of the object in very simple statements that described what we were doing and positively reinforced her with praise and pets: “Chaser, catch ___. Good dog! Chaser, shake ___. Good dog! Chaser, fetch ___. Good girl, Chaser!”

  After a few trials with different objects, Chaser knew what to expect, and her behavior briefly made me fear she had lost interest in what I was doing. When I said, “Chaser, this is ___,” she lay down on the floor and tilted her head as if she were completely ignoring the object and what I did with it. She remained lying on the floor, seeming utterly complacent, even bored. But as soon as I said, “Chaser, find ___,” she sprang to her feet and raced to find the object.

  As she did so I repeated, “Chaser, find ___, Chaser, find ___,” in a soft, encouraging tone until she found it. This I greeted with a triumphant “Good girl, Chaser!” followed by a round of play with the object.

  We did this many times for each toy, and I was curious to see whether as time went on Chaser needed fewer repetitions to learn the name of a toy. My criterion for saying she had indeed learned a word had two stages. First she had to select the correct object out of a group of objects that included seven other objects whose names she had learned. I called this the 1-of-8 test. And then she had to do the same thing seven more times in a row over the course of a day or so, each time with a different set of seven other objects whose names she knew as distracters. I called this the 8-of-8 test. After asking for the newly learned object in a group of eight toys, I also asked for the seven previously learned objects by name as a way to rehearse and test prior learning.

  If Chaser missed fetching any object by its name in the 1-of-8 or 8-of-8 tests, I gave her more training and play with that object alone, with no other objects in view. She missed here and there, but her performances on the 1-of-8 and 8-of-8 tests were usually 90 to 100 percent correct.

  As we did this with more objects I also needed to assess Chaser’s long-term memory of the objects’ names. I had to be sure that Chaser wasn’t freeing up memory space for new object names by forgetting older ones. So every month I informally tested Chaser’s retention of her complete vocabulary, to that point in time, with random sets of twenty objects on the floor in front of her. In all these tests over a period of three years, Chaser always got at least eighteen of twenty right. At the end of that time it took fifty-one sets of twenty to test her long-term retention of the names of 1,022 toys, a process that I spread over about two weeks every month.

  I became an expert at evaluating toys for Chaser’s play and training. I could take a brief look at a stuffed animal and gauge if it would last a week or a year without needing to be sewn up. I was always looking for the sturdiest ones possible. The growth in Chaser’s flock meant that there were multiple Frisbees, balls, and stuffed lions, tigers, and bears. Despite these similarities, every object had to have unique features that Chaser could distinguish visually. Over time it became harder and harder to find toys that weren’t highly similar to ones we already had.

  Occasionally Sally and I splurged ten dollars on a dog toy from the pet store, especially during after-Christmas sales. And I was always looking for the perfect Frisbee. I tried to stick to cloth Frisbees as opposed to plastic ones with hard edges. But I bought the majority of the toys mainly at the Salvation Army store, which was closer, and the Miracle Hill thrift shop, which was much cheaper. The Salvation Army store wanted seventy-five cents or a dollar per toy, whereas Miracle Hill would sell a big plastic garbage bag full for a couple of bucks.

  Sally was extremely patient as the house filled up with toys. Although we bought many large Rubbermaid containers to store them, there were always at least fifty toys strewn around for training, testing, and pure play. But sometimes the clutter of toys got to be a little too much for Sally and we had to do a rapid cleanup. This got a little easier and more pleasant once Sally decided to teach Chaser to clean up her own toys the same way she’d taught Robin and Debbie when they were small and later helped Debbie teach Aidan.

  “Clean up, clean up. Everybody clean up,” Sally sang, as she picked up one of Chaser’s toys and dropped it into a plastic storage tub in the middle of the living room. Attracted by her singing, Chaser looked at Sally, head cocked to one side with curiosity. “Clean up, clean up. Everybody clean up,” Sally continued singing. She picked up two more toys and gave one to Chaser, who took it eagerly in her mouth. Continuing to sing, Sally pointed at the plastic tub and dropped the toy she was holding into it. Chaser brought her toy over in response to Sally’s song and pointing, and dropped it into the plastic tub.

  “Good girl, Chaser!” Sally said, before resuming her song and picking up more toys for Chaser to take and drop in the plastic tub. Midway through the cleanup, Sally stopped picking up toys for Chaser and simply pointed at the ones that were still scattered around on the floor and the furniture. It didn’t take too many repetitions of this song and coaching for Chaser to learn the cleanup game. She enjoys it, too, coming eagerly when she hears someone sing, “Clean up, clean up. Everybody clean up.”

  Later I learned that telling Chaser “Clean up, and we will play Frisbee in the yard” makes her even happier to play the cleanup game. She darts around picking up her toys, and as soon she has dropped the last one into a Rubbermaid container she heads for the door with her tail wagging.

  Sally also sewed up dozens of toys over the years, especially when she became exasperated by my duct tape
repairs. That did not include beanbag-type toys, however. Early on we learned to avoid these after Chaser shook one vigorously, a seam ripped, and the beans flew everywhere.

  As Chaser’s flock expanded to include more named objects, the likelihood that her correct answers were the result of chance became smaller and smaller. That was because the possible answers were not only the named objects in the groups of eight or twenty, but all the objects whose names she had learned at the time of the test. The more object names she learned, the more impressive her consistent, very high level of accuracy became.

  The probability of her correct answers resulting from chance was small in her first tests, and her correct answers were well above the threshold that made them statistically significant. In the later tests the probability that her correct answers resulted from chance was vanishingly small. Chaser’s proper noun learning reached the point where the probability that her correct answers resulted from chance was less than 1 in approximately 20 million.

  However, the informal 1-of-8, 8-of-8, and 20-of-20 tests were subject to criticism that I was, knowingly or unknowingly, giving Chaser visual cues about which object to fetch. So every month I did a formal 20-of-20 test as well. I took twenty objects from her flock at random, reaching blindly into the plastic tubs where we kept them, and wrote their names down. After brief rehearsals with each of these twenty objects, I put them in another room so that neither Chaser nor I could see them and I could not possibly give her an unintentional visual cue about which one I wanted. And then I asked Chaser to go and fetch each one by name.

  The first time we did this, Chaser got 18 of 20 right. Thereafter her performance on the formal 20-of-20 tests was consistently in the 90 to 100 percent range. In fact, she always got at least 18 out of 20 correct on the formal as well as the informal test. When she missed fetching an object by name in any 1-of-8, 8-of-8, or 20-of-20 test, I gave her additional training with that object alone, with no other toys in sight, before testing her again.

  All told, our language training and testing sessions amounted to four to five hours a day. Weather permitting, I gave Chaser two to three hours of other physical activity a day outside the house. Some of the outdoor time was devoted to vigorous play with her named toys. But it also included agility play, tracking and stalking, and hikes in the nearby mountains.

  In the backyard I set up an agility course with jumps, a tunnel, obstacles to crawl under, and stakes to weave in and out of. Chaser loved running the course, and my directions for her to run it in different directions and patterns were another opportunity to teach her words. Every run through the course ended with my sailing a Frisbee for her to catch triumphantly.

  Some days we took the forty-minute drive to sixty acres of forest we own on the Tyger River, southwest of Spartanburg. Chaser loved jumping over logs and exploring under bushes as we hiked to a spot on the river with a wide bank of flat rock. This was perfect wading water for her to splash into while retrieving sticks and balls I tossed for her. Walking the land, she darted here and there to investigate animal scents, always on the move, until we climbed back into the car, where she curled up and snoozed until we got home, at which point she was ready for round two.

  At five months old Chaser knew more than fifty words, including those for the basic obedience behaviors. More important than the number was that we were both having lots of fun and she was eager to herd more toys, and more names, into her growing flock. Outside of training sessions, she often initiated play with her named toys and loved engaging in activities with them that mimicked herding sheep. A sequence of chasing, catching, bringing back, and gathering together a group of toys was deeply involving and rewarding for her.

  As Chaser approached six months of age, intensive practice was speeding up her word learning so that she needed fewer and fewer trials per word. I could see her response time—animal scientists call it latency—getting shorter and shorter between the moment when I said, “Chaser, find ___” and the moment when, eyes shining and tail wagging triumphantly, she brought back the correct surrogate sheep. She seemed to be learning words so quickly that I decided to try an extreme test.

  I brought out a new object, a fleece-covered brown and white stuffed pony, about nine inches high and about fourteen inches from nose to tail. On the pony I had written the name Puddin. With Chaser sitting in front of me, I pointed to the stuffed pony and said, “Chaser! This is Puddin.” Then I immediately took it into the bedroom and placed it on the floor among seven other objects. Four were familiar objects whose names Chaser already knew, and three were novel objects she had never seen. Including three completely unfamiliar objects in addition to Puddin made the test very stringent, because it dramatically increased the possibility of error.

  I came back in front of Chaser and asked her to find two of the previously learned objects, which she did without a hitch. There were still six objects on the floor in the other room: two familiar ones whose names she’d learned previously through repeated trials; three completely novel objects; and one, Puddin, that she’d seen and heard the name of only once. I then said, “Chaser, find Puddin.”

  Chaser sprang to her feet and dashed into the next room. In another flash of fur she stood before me wagging her tail and grinning from ear to ear with Puddin in her mouth. I immediately tested her twice more, and four more times the next two days. Each time I put Puddin down among a different set of seven other toys. Each time Chaser was perfect.

  There was no doubt about it. Chaser had learned Puddin the pony’s name in a single trial. Identifying the new object correctly after hearing its name only once indicated that Chaser had achieved a form of referential understanding. Somehow she had grasped the idea that objects can have names. She had learned that my pointing to an object and saying “This is ___” meant I was going to announce the object’s unique name. To use the terms of childhood language learning research, Chaser had learned two referential social cues for indicating word meaning. On top of associative learning she had now added at least the first stage of intuitive learning via symbols. This was supposed to be impossible for nonhuman animals.

  Chaser’s intuitively understanding that objects can have names was a defining moment for her as a learner. Chaser did not consciously realize what had happened, any more than eighteen-to-twenty-four-month-old toddlers consciously realize that they are suddenly understanding words in a new and fuller way. But I knew that Chaser had crossed a threshold and entered a whole new world of learning.

  Random testing showed that Chaser could learn as many as ten new words a day, about as many as a nine-year-old child learns. Unlike a nine-year-old child, however, Chaser needed very extensive rehearsal time to retain this many words. So we settled into a pattern of one to two new words a day, which she could lock into long-term memory with a few days’ worth of rehearsal sessions off and on through the day. Brief pilot testing suggested she could have learned three to four proper nouns a day, but I was also focusing on teaching her other elements of language, including common nouns and learning by exclusion.

  At the age of seven and a half months, Chaser knew more than two hundred words, as many as Rico. That Chaser was now reading my mind through the words I spoke to her gave me goose bumps. It made me think of the moment when seven-year-old Helen Keller first understood the connection between words and the things they represent. For more than five years after a terrible fever left then nineteen-month-old Helen blind and deaf, she lived in darkness. She was almost like a feral child, subject to violent tantrums of frustration. Her desperate parents brought in twenty-year-old Anne Sullivan, herself nearly blind, to try to teach Helen. Every day Anne traced letters on the palm of Helen’s hand, trying to communicate that these tracings spelled words that represented objects such as a doll she gave the little girl as a get-acquainted present.

  Helen could not grasp that there was a word for everything and that everything had a word—or many words—to describe and represent it. In a rage at not being to able to understand wha
t Anne meant by signing the letters m-u-g in her palm, Helen broke the doll that she was carrying everywhere.

  About a month later, Helen and Anne were at a water pump on the Kellers’ farm. As water poured over Helen’s hand, Anne spelled out w-a-t-e-r on the palm of her other hand. Over and over again Anne spelled the letters: w-a-t-e-r, w-a-t-e-r, w-a-t-e-r, w-a-t-e-r.

  Suddenly Helen burst out with a cry of joy. It was the defining moment of her life. The eyes in her mind opened and she saw that w-a-t-e-r meant the substance pouring over her hand, the substance she drank and encountered in other ways every day. Her genius at last set free, she was now on the path to gaining full command of language. Her learning exploded, and she grew up to become one of the most extraordinary and influential figures of the twentieth century.

  Seeing Chaser’s vocabulary increase day by day and week by week, I raised my sights from merely matching Rico to surpassing him. The goal for learning proper nouns was now a thousand words. A thousand-word vocabulary would be enough to show that Chaser’s long-term memory system was extensive and robust. It was also enough to demonstrate her understanding of words as more than object names and in more contexts than simply fetching objects. If the skeptics didn’t find Chaser’s knowledge of a thousand proper nouns in combination with multiple common nouns and verbs convincing, they weren’t going to be more favorably impressed by two thousand or three thousand proper nouns.

  In the meantime I wanted to show Wayne West what a smart puppy we’d gotten from him, and I wanted to talk to him about giving Chaser a chance to herd sheep.