The Education of Sarah

As the brightest of the big apes, the chimpanzee may be man's nearest intellectual neighbor. How near? Science has long sought to discover in the intelligent chimp the gift of language, the incomparable skill that distinguishes mankind from all other living things. Until now, that search has been fruitless; the chimp lacks the capacity for speech that is innate in every normal human infant. But in Psychology Today magazine, Psychologist David Premack of the University of California at Santa Barbara demonstrates that the chimpanzee can converse with man in ways other than by the tongue.

Premack's prime evidence is Sarah, a seven-year-old female chimp with a working "vocabulary" of more than 120 words. Sarah can not only comprehend the meaning of these words but can dip into her glossary to answer questions and build original sentences of her own.

Cognitive Ability. To teach Sarah, Psychologist Premack devised symbols cut out of plastic and mounted on metal bases so that Sarah could "write" them on a magnetized board. With practice, Sarah learned that a blue triangle meant an apple, a red square a banana. In time she mastered symbols identifying each of her four trainers, plus other symbols identifying colors and familiar objects such as a pail, a cup and a dish. For example, stands for red, for dish.

All this was mere rote learning. To develop an understanding of syntax. Premack introduced a new symbol representing the preposition on. Given two familiar color symbols representing green and blue, for instance, and by watching the trainer place the green on the blue and vice versa. Sarah eventually came to understand the preposition's purpose. This was one of her first sentences, condensed to a three-symbol command: Green goes on red. Before long, Sarah knew how to obey commands in as many as twelve possible color combinations at an impressive accuracy rate of 80% to 90%.

On one memorable occasion, which Premack records with almost parental pride, his pupil invented a sentence-completion game and invited her trainer to play. The trainer had set up some nonsensical physical-relation tests involving objects and colors--red is on (i.e., superimposed upon) green, green is on banana, apple is on orange--to test Sarah's proficiency in word order. Abruptly, Sarah took over. She began a sentence "Apple is on ... ," and then arranged a number of possible completions, only one of which she considered correct: "Apple is on banana." Then she led her trainer through the multiple choices until her human student caught on to the game.

Over two years, Premack and his assistants trained Sarah in the use of verbs, sentence structure, questions and conceptions, the last being the cognitive ability to grasp not only the root meaning of the word-symbols but their application in totally unfamiliar contexts. Having taught her to associate the color red with apple and the color green with grape, says Premack, "we then tested her comprehension of the conception 'color of.' " He was not surprised when Sarah demonstrated her ability to assign the characteristic "color of" to totally unfamiliar objects: that the redness of an apple, for instance, could also be found--and recognized by her --in a persimmon.

Manifestly Brilliant. Premack cites an experiment in which Sarah was given a real apple and asked to select those symbols--red or green, round or square--that characterized the apple. She did this readily. Then the apple was replaced with its symbol, the blue triangle, and Sarah was again invited to select its qualities. With unfailing confidence, she attributed to this totally unapple-like symbol the same qualities of roundness and redness--"evidence," writes Premack, "that the chimp thinks of the word not as its literal form (blue plastic) but as the thing it represents (red apple)."

On the basis of two years' work with one chimpanzee. Psychologist Premack sensibly does not claim anything more than Sarah's own and manifestly brilliant record. But his mind is at least as open as hers. "This does not mean that she can produce all the functions of language, or that she can do everything a human can," he writes. "But then," he adds, obviously unconvinced, "we have only been working with her a relatively short while."

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