Kanzi: The Ape at the Brink of the Human Mind (32 page)

Comprehension has been relatively neglected by linguists, for two reasons. First, it is much more difficult to study than word production, particularly when tests require that infants cooperate in test situations where they may be asked to label or identify things that they are not at the moment thinking about or wishing to play with. Second, linguists’ obsession with the putative
innateness of language capacity has focused attention on production and away from comprehension. And yet, increasingly, psycholinguists are coming to acknowledge that comprehension is at least as fundamental as production in the acquisition of language, if not more so. It is also being recognized as immensely complex.

We usually think of language as being composed of discrete words that are assembled into phrases and sentences—this is how it appears when we hear language spoken and, particularly, when we see it written. But the sounds of language when they enter the ear are anything but discrete. Viewed on a spectrograph, a sentence looks like a continuity of sound, with intermittent jumps in amplitude, but with little clue as to where one word ends and another begins. Moreover, the same word in different sentences may look very different. For this reason, it has been unexpectedly difficult to devise a computer program that can decode human speech. And yet, before she reaches the age of one, a human child has already begun to do just that. Beginning with phrases, the child soon moves on to decoding sentences, a process that paves the way for language production.

Despite progress in breaking language down into its components—such as intentionality, rule learning, imitation, fast associative mapping, and sequencing—there is no widely accepted explanation of how language acquisition occurs. We know that children need early exposure for efficient language acquisition, but it remains a mystery how this puts into place an understanding that words are referential items and that, properly structured, they create information-rich sentences.

The Chomskian innatist view of language acquisition explains the child’s gradual ability to learn to speak, despite the cacophony of language to which she is exposed, as the result of a developmental switching on of a parsing device, a brain module designed for the purpose. There is no anatomical evidence for the existence of such a structure, and the hypothesis effectively rests on a default premise: namely, that no other hypothesis offers an adequate explanation. It is true that the process of language acquisition through which most of us pass appears to be a near miracle, given the absence of what could be considered
effective teaching. But that is an inadequate rationale for assuming the necessity of a unique, undetected brain structure. A plausible alternative hypothesis is that comprehension drives language acquisition.

Children, as they learn to acquire language, make some linguistic mistakes, but their number is remarkably few, and they are often on the order of incorrectly generalizing correct rules—such as “goed” for went. A minimization of production errors would occur if children came to comprehend much of what others were saying to them before they learned to speak. It has long been recognized that comprehension precedes production, both at the single-word and sentence stages. Comprehension can therefore put in place the fundamental rules for production, with context playing a large role in giving meaning to words that are heard by the child. When they are learning to talk, children do not appear to be building up a complex grammar out of single word units and an innate parsing device. Instead, they seem to be pulling apart the syntactic structure inherent in the speech around them, through the help of speakers who mark these syntactic units by their intonation and use of phrase, and by the context of what is being said. In other words, a child learns language by listening and paying attention, not by talking.

Although by no means universally accepted as the central aspect of language acquisition, comprehension is being taken more seriously than it used to be, not least in the innateness (uniqueness) debate. With Kanzi, we had an opportunity to explore the elements of comprehension that emerged as a result of his early exposure to spoken language. If his abilities were to extend beyond comprehension of single words, we would have further evidence of evolutionary continuity of language abilities.

As I described in an earlier chapter, Kanzi showed evidence that he comprehended spoken English words from a very early age. The test we did when he was four years of age showed that he could choose the correct lexigrams with sixty-five spoken words. But it was also clear to me that he understood phrases too, albeit quite simple ones. As the years passed, his comprehension appeared to expand in range and become more sophisticated.

During our day-to-day activities, we constantly attempted to explore the limits of Kanzi’s comprehension. For instance, one day he and I were down by the river and, as always, Kanzi had his ball with him. Balls had been Kanzi’s favorite toys since he was six months of age. He loves all sorts of balls, large and small, soft and hard, and is never really happy unless he has at least one ball with him, but preferably two or three. His favorite balls are shiny ones that look rather like the genital blossoms or attractive sexual swellings that adolescent female bonobos sport most of the time. When the other bonobos want to tease or hassle Kanzi, they will take his ball if he is not looking at it. Never has Kanzi failed to react when I say, “So and so is about to get your ball.” He immediately whips around and rushes to grab his ball back. When Kanzi has five or six balls and is trying to keep track of all of them with the other bonobos around he has a real job, for one ball or the other is always rolling away where another bonobo can grab it, and as he hurries to retrieve it, others roll away from his pile. We have occasionally made videotapes for Kanzi’s viewing in which an imaginary gorilla steals one of his balls and plays with it. Kanzi is riveted to the screen when such scenes appear and must rush to locations he has seen on the television immediately afterward to search for the ball. Kanzi has an uncanny memory for his balls; he can recall where he has left one days, months, and even years later.

On this particular day when we were down by the river, I decided to ask Kanzi, “Can you throw your ball in the river?” I knew this was something he had never done before and something no one would have ever asked him to do, as we generally tried to keep everything out of the water except sticks and rocks. However, I decided to violate one rule today, just to see if Kanzi could understand such an unusual request. He promptly tossed the ball in the river. On another occasion, as we were walking through the forest with his half-sister Panbanisha, I said, “Kanzi, would you please give Panbanisha an onion?” He looked around for an onion patch, pulled up a bunch, and handed them to Panbanisha. It might be thought that in such sentences all Kanzi heard was “Kanzi, xxxxx xxx
xxxxx xxxx Panbanisha xx onion,” and put two and two together. After all, he could not have given Panbanisha to the onion. But we noticed that, where confusion was possible, such as, “Can you throw a potato at the turtle?” he rarely made mistakes. (In this case, the mistake would be throwing the turde at the potato.)

Most salient, however, were conditional sentences. One day, for instance, we were visiting Austin, who was busy with a task. As a reward for completing the task, Austin was given cereal, which Kanzi desperately wanted and kept requesting. I knew that Austin would become angry if Kanzi took the cereal, and told Kanzi so. While all this was going on, Kanzi was playing with a monster mask that we had brought in the backpack. Austin was very interested in the mask, so I thought I would offer a deal. I said, “Kanzi, if you give Austin your monster mask, I’ll let you have some of Austin’s cereal.” Kanzi promptly got the mask and gave it to Austin, and then pointed again to the cereal. It had been a linguistic bargain, and Kanzi had understood.

We recorded many such examples of Kanzi’s understanding complex sentences—at least, when the subject at hand was of interest to him. When Kanzi wasn’t interested, he either did not understand or simply acted dumb. (I knew he was capable of being contrary when asked to do something he didn’t want to do, often doing the exact opposite.) A compilation of these carefully recorded anecdotes about the extent of Kanzi’s comprehension was regarded as insufficient evidence for most people, especially the skeptics. For this reason we decided we would embark on a strictly controlled study, comparing Kanzi with a human child, Alia. Our goal was not to build a complete picture of their comprehension, but rather to discover what kinds of syntactic markers, if any, they were becoming sensitive to.

We developed a series of strict criteria for the test, to ensure that Kanzi and Alia were not inadvertendy “trained” during the trial and that we did not cue them. Very simply, in entirely separate but identical experimental settings, we planned to present them
with a series of novel sentences (660 in all) and monitor their responses. Initially, the experimental setup was a little unsettling for both subjects, as the person asking the questions had to be out of sight. The questions therefore were delivered by one experimenter as a disembodied voice, from behind a one-way mirror. A second experimenter sat with Kanzi and Alia, sometimes being part of the ensuing action, but always recording what was done. This experimenter wore headphones with loud music, so he or she could not hear the sentences being directed at the subject. The sessions were also videotaped, so that they could be scored by an independent observer.

We were unsure at the outset how extensive Kanzi’s and Alia’s comprehension competences would be, and so we were prepared to change the complexity of what we asked as the test proceeded. It turned out that we had to increase the complexity of sentences, for both subjects. Whatever the complexity, however, we made sure that many of the sentences were unusual, such as asking them to wash hot dogs. This sometimes caused puzzlement, but mostly comprehension won through. We devised five major types of sentences (with subgroups, giving a total of thirteen) designed to test issues such as word order and complexity of structure.

By the end of the nine-month test period, both Kanzi and Alia had demonstrated a well-developed ability to comprehend all types (and subtypes) of sentences, with Kanzi scoring just a little ahead. Overall, Kanzi correctly answered 74 percent of the sentences, while Alia’s figure was 65 percent. Often, when errors were made they were semantic or through inattention, not a misunderstanding of the structure of the sentence. For instance, when I asked Kanzi to “Pour the milk on the cereal,” he poured the milk on the mushrooms. He performed the correct action according to the structure of the sentence, but with the wrong object. Similarly, Alia once put peaches into yogurt rather than into the tomatoes, as she had been asked.

On another occasion, Kanzi clearly mixed up words, and thought he was doing as I had asked, which was to “Put the paint in the potty.” He promptly picked up some clay (a similar play object to paint), and put it in the potty. I said, “What
about the paint?” Kanzi put more clay in the potty. I said, “Thank you,” but “now put
the paint
in the potty.” Kanzi clearly thought me a little dumb, and so brought me the potty and placed it right in front of my face so that I could see that he had done what I was so persistently asking.

One difficulty we had not foreseen, but which proved illuminating, concerned requests to retrieve an object from another location, such as, “Go to the group room and get the ball.” If there was a ball where Kanzi was sitting when he heard the request, he often glanced at it, glanced toward the group room, perhaps touched the ball, and, 50 percent of the time, handed it to the experimenter. We thought of another way of asking the question, which linguistically is more complex: “Get the ball that’s in the group room.”

Structures such as “that’s in the” are known by linguists as embedded phrases and are thought to be uniquely reflective of human thought in their recursive structure. In such sentences, one part of the sentence refers back to another. In order to understand the meaning, one has to know that one word refers to a specific word that occurred earlier in the sentence, and that the second word, in some way, changes the meaning of the first. For example, in the sentence, “Get the ball that’s in the group room,” the words “group room” refer back to the word “ball” and specify a particular sort of ball. Since parents have not been observed actively explaining how “recursion” works to children, yet children understand such sentences, linguists assume that an innate grammatical device permits them to decode such embedded references.

For Kanzi, the embedded phrase helped clarify the request, not confuse him. When he heard such sentences he tended to set off in the direction of the required location, with rarely a glance at a decoy object in front of him. He scored
77
percent correct answers with such requests, compared with 52 percent for Alia.

Oddly, one of Kanzi’s greatest problems was with sentences that were grammatically the most simple, in which he was asked to do something with more than one object. For instance, if I said, “Give Sue the hat and the potato,” he would readily give
me the hat, but not the potato. He would then give me the potato if I reminded him. Sometimes Kanzi forgot the first object, other times it was the second one. It seemed that as soon as he focused on one, the other was forgotten, suggesting that the problem was one of short-term memory. There was no inherent relationship between, in this case, the hat and the potato that helped him respond correctly. If I said, “Put the hat on the potato,” he had no difficulty remembering both objects, though he might simply place them side by side rather than putting the hat on the potato. Such errors revealed the way in which sentence structure aided comprehension, both for Kanzi and Alia.