Chimpanzees' Ability to Use Language in a Rudimentary Way
Many researchers wonder if chimpanzees are really able to use language in a rudimentary way, or if it is just created by operant conditioning. Psychologists realized, as far back as 60 years ago, that chimps would never be able to learn spoken language. They do not have the specialized tongue, lips, teeth, facial muscles, and palate that humans do to make the vast array of speech sounds that humans do. Researchers have instead tried to teach chimps some visual form of language.
An example is Beatrice and Allen Gardner's experiment with American Sign Language (ASL). They started their research with a one-year-old chimp named Washoe, whom they raised like a child. The Gardners and their researchers signed to Washoe and one another just like deaf parents might do. Whenever Washoe signed correctly, she was rewarded. Because Washoe was raised amongst her caretakers, she had a lot of practice signing throughout her daily life. After four years of training, she had acquired about 160 signs. The Gardners saw many similarities between Washoe's progress and that of a young child learning spoken language. Once she had learned a certain sign, she appropriately generalized its use to other objects or activities. For example, when she learned the sign for "more" to ask for more tickling, she used it to ask for more food or more play. Many of her mistakes seemed similar to ones children would make. After she had learned eight or so signs, she started using them in combinations, such as "more sweet;" later, she combined three or more signs to make statements or commands. By the age of five, the Gardners thought that her language resembled a three-year-old child's.
In a different research project, psychologist David Premack taught a chimp, Sarah, language using small plastic symbols of different colors and shapes, which each stood for a word. Sarah learned to make simple sentences by arranging the symbols on a board. This system is easier for a chimp than ASL is. Because the symbols were right in front of her, she could use them as cues to remember the meanings. One disadvantage was that Sarah became mute when she didn't have her symbols.
In another research project, Duane Rumbaugh taught a chimp named Lana to use a special typewriter linked to a computer. It had fifty keys, each showing a geometric configuration that represented a word. When Lana typed a configuration, it showed up on the screen in front of her. She learned to correct herself by checking the sequence of configurations as they appeared. Lana learned to respond to humans who "talked" through the computer and she initiated conversations. When Lana came across an object that she hadn't been taught a word for yet, she sometimes made up her own.
Some researchers have argued that language-trained chimps use symbols and signs meaningfully and accurately. They are able to refer to things that have been...