Chaser_Unlocking the Genius of the Dog Who Knows a Thousand Words

by John W. Pilley

  As I mentioned earlier, Chaser learned the concept of “toy” not on physical characteristics, but based on an abstract functional characteristic. Toys were objects she knew by their individual names and could play with. Everything else was a non-toy. It was fascinating that she grasped the higher-level, more abstract concept of “toy” first.

  As Chaser’s learning continued through the fall of 2006, I was of two minds. All the experiments Chaser and I had conducted so far—proper noun learning, independent meanings for two elements of syntax, and common noun learning—showed that her language abilities reached far beyond those documented for Rico. The evidence was piling up for a major scientific paper in a peer-reviewed journal.

  Part of me was itching to document Chaser’s achievement for its own sake, as a contribution to the understanding of learning, and as a stimulus to other scholars. The other part of me didn’t want to slow down research in order to write such a paper, which would limit the time I could spend with Chaser day in and day out. Instead, I wanted to press ahead and extend Chaser’s language training. Her ability to take an object in her mouth, or nose or paw it, on command showed that she could respond correctly to sentences with two elements of grammar: a verb and a direct object. In the early 1980s Louis Herman and his colleagues at the University of Hawaii studied the ability of two bottlenose dolphins, Phoenix and Akeakamai, to respond correctly to sentences containing two, three, four, and five elements of grammar, including verbs, direct objects, indirect objects, prepositions, and adjectives and adverbs. Understanding three elements of grammar sentences was the next step for Chaser in my mind.

  Working alone, I had to make a choice. If I didn’t write a paper now, who knew what might prevent me from doing so in the future? Ultimately I couldn’t take the chance of not documenting Chaser’s learning as soon as I reasonably could. It would be a terrible waste if her learning wasn’t shared with others.

  More important than any concern I might have about being able to write a paper later, however, was my desire to honor Chaser’s achievements. By this point she had achieved nearly all of my initial research goals for her, matching or exceeding Rico’s learning and doing so in a way that met the objections that the Yale research psychologist Paul Bloom and two other childhood language learning researchers, Stanford’s Ellen Markman and Maxim Abelev, had raised about the Rico study. These objections all involved language understanding that one-to-three-year-old toddlers display but that had never been demonstrated or was subject to question in animals.

  In assessing the Rico study, Bloom emphasized that children learn words by overhearing them, the implication being that animals never did this. Yet it seemed plain to me that Chaser had learned “sheep” and quite a few other words by overhearing them. All of my experiences with dogs over the years made me suspect that many dogs commonly understood the meanings of a dozen or more words they heard frequently, such as the obedience commands or the words “walk” and “treat.”

  In addition to “Let’s go to the sheep,” Chaser responded enthusiastically to “Let’s go for a hike,” or “a walk” or “play Frisbee.” If Sally said, “I’m going over to Sue’s” or “I’m going over to Nora’s,” Chaser headed straight to the door. As soon as Sally opened the door, Chaser ran to the edge of the road and waited there for her.

  There were also words she learned by overhearing that she preferred not to hear. If we said, “Chaser, let’s go to the store,” she looked peeved and didn’t want to come. Her ears and tail went down, and her usual grin turned into what looked like a slight frown. She came along reluctantly only if we pressed her. She had learned that going to the store meant sitting in the car waiting for one or both of us to return from shopping. Where was the fun in that?

  Another thing Chaser didn’t like was taking her monthly heartworm pill. If Sally said, “Chaser, come get your pill,” she slunk away to the bedroom and tried to avoid it. Sally got around that by saying, “Chaser, come get your pill and I’ll give you a treat.” That brought Chaser quickstepping to swallow her pill dutifully and then enjoy a treat.

  The real problem with overheard word learning by an animal was demonstrating it empirically. To show that an animal’s exposure to a word was only by overhearing it, with no explicit teaching, would require a 24/7 visual and audio record of the animal’s life to that point. I put that aspect of Chaser’s learning to the side in my mind, unsure whether I should include it in a peer-reviewed paper.

  Bloom also said that children are able to learn words by being shown an object and hearing a person name it, again with the implication that animals could not do this. Showing Chaser an object and naming it became my basic method for teaching her words. Once Chaser learned the concept that objects have names, as I described in chapter 9, my tests showed that she learned the names of objects on one trial when she was shown an object and told its name. When I tested retention after ten minutes and twenty-four hours, I found that she needed additional rehearsal to process the learning into long-term memory. But toddlers also need rehearsal to lodge new words into long-term memory.

  Another of Bloom’s reservations about Rico’s learning was that “it is always Rico’s owner who is communicating with him. . . . Yet, if Rico really is learning sound-meaning relations . . . it should not matter who the speaker is.” That seemed reasonable to me. As Chaser’s word learning advanced, I brought other people in as trainers. Sally, Robin, and two Wofford undergraduates who assisted me at different times, Caroline Reid and Katie Grainger, all taught Chaser proper noun object names. I was also planning to do a set of formal blind and double-blind tests of Chaser’s learning, in which others beside myself gave her the commands to perform language tasks.

  Rico was only tested in fetching objects by name, and Paul Bloom’s biggest question was whether a dog could show knowledge of words in relation to more than one action. As I’ve described, Chaser showed this in learning to take named objects in her mouth, or nose or paw them, on command, including objects she’d never been asked to do any of these things with. This demonstrated both that she understood independent meanings for two elements of syntax, an object name and an action verb, and that she understood novel combinations of objects and commands.

  Bloom also questioned whether animals could learn common nouns. I was looking forward to documenting Chaser’s understanding of “ball,” “Frisbee,” and “toy” as common nouns.

  Markman and Abelev seconded Bloom’s reservations and added two of their own. First they were skeptical that language-trained animals could progress beyond “mutual exclusivity,” the assumption that things have only one name. Markman and Abelev observed that in the early stages of language learning five-month-old infants “expect that a novel word will refer to a novel object rather than a familiar one,” but by seven months most babies learn that this “mutual exclusivity” does not always hold true and that a single thing can have multiple names. They learn that a set of common nouns such as “cat,” “kitty,” and “pet” can all refer to the same thing, and that a set of proper noun names and nicknames such as “Elizabeth,” “Lizzy,” and “Sweetie” can all refer to the same person.

  When I read Markman and Abelev’s article on its publication in November 2004, Chaser was seven and a half months old. At that point she knew that she was also called baby, Puppy, girl, and sweetie, as well as combinations of those names and nicknames. Simply by overhearing the various names, she knew that Sally was also Mom and Nanny, and that I was Pop-Pop, Dad, John, and Pilley. She knew that food had many names: breakfast, lunch, supper, treat, chew stick, and bone. She knew that the command to jump had three labels (“hoop,” “up,” and “over”) and that the command to come had four labels (“here,” “come,” “hurry,” and “right now”).

  In her common noun learning, Chaser showed that she could distinguish balls and non-balls, Frisbees and non-Frisbees, toys and non-toys. She could also identify one of her balls both by its proper noun name and as a ball and a toy, or one of h
er Frisbees both by its proper noun name and as a Frisbee and a toy.

  Thus Chaser demonstrated the one-to-many and many-to-one mapping of words and things that both Bloom and the team of Markman and Abelev doubted dogs could achieve.

  Markman and Abelev’s second big reservation about the Rico study had to do with learning by exclusion, also known as reasoning by exclusion. Rico demonstrated this when he retrieved a novel object from a group of familiar objects on hearing its name for the first time. In the absence of any external or physical cue, he apparently inferred that the novel name referred to the novel object. However, Markman and Abelev questioned whether Rico’s success really showed that he was drawing an inference.

  Markman and Abelev granted that the procedure for Rico’s “reasoning-by-exclusion test trials . . . closely parallel[ed] those used to demonstrate word-learning by exclusion in young preschoolers.” But they raised three possible objections. First they noted that Rico’s tested vocabulary only included proper nouns having a one-to-one correspondence with the objects they named. Based on this prior experience, Rico might assume that words are mutually exclusive and that thus a novel name must refer to a novel object.

  The second possibility Markman and Abelev suggested was that Rico had a default assumption that words are mutually exclusive based on other prior learning or an innate propensity. This could also make him always pick a novel object on hearing a novel name.

  Chaser’s combined proper noun and common noun learning showed that she knew that words are not mutually exclusive. She understood that objects could have more than one common noun category label (“toy” as well as “ball” or “Frisbee”) plus a unique proper noun name. And she understood that the same individual could have more than one proper noun name. Her demonstration of many-to-one and one-to-many word-object mapping put these first two possibilities to rest, insofar as her own learning by exclusion was concerned.

  The third possibility Markman and Abelev suggested was that Rico had a baseline preference for choosing novel objects. They pointed out that the Rico study said nothing about testing whether Rico had such a baseline preference. Studies of learning by exclusion in preschoolers did test for a baseline preference for novelty, and such a preference, rather than a correct mental inference, might be why Rico picked the novel object after hearing its name for the first time.

  In response to this third possibility, the Rico study researchers replied that, before asking Rico to retrieve a novel object, they first asked him to retrieve two familiar objects. This demonstrated that his choices were not owing to a preference for novel objects.

  I decided to replicate this procedure. In addition, I decided to measure Chaser’s baseline preference for novelty before her first opportunity to learn a word by exclusion.

  I did not attempt to train Chaser to learn by exclusion. But I felt confident she could do it, based on Rico’s example and, more important, her own ability to grasp a series of abstract concepts. Chaser grasped that objects could have names, and then became able to learn a new object name on one trial. She learned that common nouns refer to categories, and then became able to distinguish categories based on shared physical characteristics (balls versus non-balls and Frisbees versus non-Frisbees) or more abstract shared functional characteristics (toys versus non-toys).

  Before testing Chaser’s ability to learn a word by exclusion, I tested her baseline preference for novelty. I took eight familiar objects and rehearsed Chaser in retrieving them by name. The next morning, with Chaser waiting in my study upstairs so that she could not see what I was doing in the living room, I put the eight familiar objects and two novel objects behind the couch. Then I called Chaser downstairs and asked her to retrieve each of the eight familiar objects by name. She did this without a hitch.

  Over the next week I repeated this procedure seven times, each time with two different novel objects and eight different familiar objects. Because Chaser now knew about nine hundred proper nouns, there was no shortage of familiar objects.

  In all eight trials, Chaser only retrieved the familiar objects I asked for by name. This established that she had a zero baseline preference for novelty.

  Next I rehearsed Chaser on retrieving seven different familiar objects by name, in order to be sure that she still remembered their names. After that I had Chaser wait upstairs so that she could not see what I was doing, and I put the seven familiar objects behind the couch along with a novel object that I had not used in looking for a baseline preference for novelty. When I called Chaser to come downstairs into the living room and sit in front of the couch, I first followed the Rico researchers’ procedure by asking her to retrieve two familiar objects.

  And then I said, “Chaser, find Lounge. Find Lounge.”

  Chaser padded behind the couch while I sat with my back to her. Several seconds passed without her bringing anything to me. I repeated, “Chaser, find Lounge. Find Lounge.” I waited ten more seconds, marking the time by the clock above the television, before turning around to see what Chaser was doing, or rather, not doing.

  She was just standing over the novel object and the remaining five familiar objects. I turned back around quickly to make sure I didn’t unknowingly give her an identifying cue. And then I repeated, “Chaser, find Lounge. Find Lounge.” Over the next minute I repeated those words several times, but she still did not return with an object.

  I was wondering how much longer I should wait when Chaser slowly came around the couch. In her mouth was a plush miniature chair from a dollhouse set.

  “Good dog! Good girl, Chaser! You found Lounge!” thundered out of my mouth in relief and excitement. The five minutes of play with Lounge were extra joyful for me.

  The next day I repeated the procedure with seven different familiar objects and a different novel object she’d never seen before. She immediately retrieved the two familiar objects I asked her to get. And then I said, “Chaser, find Chipmunk. Find Chipmunk.”

  Again there was quite a long pause, more than a minute altogether, during which I repeated “Find Chipmunk” several times. Again she finally came slowly out from behind the couch with the correct object, a little stuffed animal in the form of a chipmunk.

  In subsequent trials, there was no delay. And Chaser made the correct inference every time. After hearing its name for the first time, she always found and brought me the novel object she’d never seen before.

  I immediately followed these novel choice trials with retention tests. I placed a novel object whose name Chaser had learned by exclusion behind the couch in a group with three novel objects whose names she hadn’t learned and four familiar objects. Immediately after the selection choice, the retention test showed that she remembered the object name. When I repeated the retention test after ten minutes and after twenty-four hours, the results were inconsistent, as they also were with human toddlers.

  With this learning, Chaser matched Rico’s demonstration of selecting an object on the basis of exclusion. She was in shouting distance of learning more than a thousand proper nouns. And she had met all the additional criteria for word learning proposed by Bloom and by Markman and Abelev. It was time to begin writing up the experiments for publication in a peer-reviewed journal. Given Chaser’s unprecedented language learning, I assumed it would be no trouble at all getting a paper published in a good journal.

  I should have known better.

  12

  Getting Published

  BY THE TIME Chaser turned three in the spring of 2007, she knew more than a thousand objects by their proper noun names. There were 800 stuffed animals, 116 balls, 26 Frisbees, and 100-plus plastic and rubber items. I began writing a paper that would share the impressive results of her learning. I hadn’t written a peer-reviewed paper in a long time, but I knew the form well. And I thought I had an excellent recent model in the Rico paper, which was distinctive not only for its content but also for its fairly conversational style, though I intended to provide a more thorough explanation of my training
and testing procedures.

  I included the full spectrum of language learning I observed in Chaser, even if I didn’t have extensive data on some aspects of it. I believed that the remarkable nature of the findings would justify publication in journal editors’ eyes. I entitled the paper “Can a Dog Learn Nouns, Verbs, Adverbs, and Prepositions?”

  My hope was that Science, the world’s most prestigious scientific journal along with Britain’s Nature, would publish the paper as a sequel of sorts to the Kaminski paper on Rico. And I hoped they’d ask Paul Bloom to contribute another “Perspective,” in which he would acknowledge that Chaser’s learning met all the basic criteria for word learning. Toward the end of the summer I told Alliston Reid that I was going to send the paper to Science.

  With a smile Alliston said, “They only give you one shot there, John.”

  “I know,” I said. “But they published the Rico paper and I’ve gotta think this is a pretty good shot, given how much Chaser has learned and how she’s met Bloom’s and Markman and Abelev’s major criteria for referential understanding. Here’s hoping, anyhow.”

  A few days after that, with my eyes blurry from reading and rereading for typos and grammatical errors, I sent the paper to Science. Several weeks later an editor at Science briefly e-mailed me to say that upon review they were rejecting the paper. There was little detail as to what might have been said about the paper during the review process or what its specific flaws might be.