Great ape language research historically involved attempts to teach chimpanzees, gorillas, and orangutans to communicate using imitative human speech, sign language, physical tokens and computerized lexigrams. These studies were controversial, with debate focused on the definition of language, the welfare of test subjects, and the anthropocentric nature of this line of inquiry.
The consensus among linguists remains that human language is unique.
Contemporary research has steered away from attempting to teach apes human language and focuses instead on observing apes' intraspecies communication in zoos and natural habitats. This includes gestures, facial expressions, and vocalizations.
1890s: Richard L. Garner
Richard Lynch Garner was the first researcher to explore in depth the communication skills of nonhuman primates. He began in 1884 studying monkeys in American zoos and later travelled to Africa to study gorillas and chimpanzees. He wrote frequently for popular journals and newspapers and ultimately had three books published on the subject, The Speech of Monkeys (1892), Gorillas & Chimpanzees (1896), and Apes and Monkeys: Their Life and Language (1900).
Garner argued that nonhuman primates have their own forms of speech. He claimed to be able to talk to the animals and act as their interpreter. His methods and conclusions were not scientific by any modern definition, but his work was nonetheless significant. For one thing, Garner studied the animals' intraspecies vocalizations, in some cases in their natural habitats. He went to great length to do so, even living inside of a cage himself to observe gorillas in Africa. This was in contrast to later language studies, which separated apes from their conspecifics (peers) and placed them in alien – human – habitats. Second, Garner pioneered the use of recording primate vocalizations and playing them back later for experimental purposes.
1930s: Cross-fostering and efforts to teach speaking
The next line of research came out of cross-fostering studies, where chimpanzees were raised in human homes as children. Primatologist Robert Yerkes launched one such project. He recruited Luella and Winthrop Niles Kellogg, scientists at Indiana University, to raise a chimp named Gua alongside their human child, Donald. In The Ape and the Child, the Kelloggs wrote that "it was very clear during the first few months that the ape was considerably superior to the child in responding to human words. She began to react distinctively to separate vocal stimuli within a few weeks after she had entered the human environment."
The Kelloggs noted that Gua made several distinct vocalizations to communicate different needs, and, accordingly, tried to teach her to speak English words. The Kelloggs were building on Yerkes' assertion:It seemingly is well established that the motor mechanism of voice in this ape is adequate not only to the production of a considerable variety of sounds, but also to definite articulations similar to those of man. But Gua did not communicate using human words. Instead of the chimp copying the humans, the Kelloggs' son Donald started copying the chimp, adopting Gua's vocalizations. Donald would use food grunts, for example, when hungry. Shortly after the Kelloggs made this observation, the experiment was discontinued. (Yerkes disapproved of Winthrop's book about the Gua experiment and had records of the project stricken from his Orange Park hub.)
After the Kellogg study, there were four similar research projects into cross-fostering. The most notable of these was conducted by Keith and Catherine Hayes with their chimpanzee Viki. Viki would lead people to places she wanted to go as well as move the hands of people onto objects she wanted them to manipulate. She would rarely point to objects that she wanted; instead she would make gestures. For example, when she wanted to help with ironing, she would move her hand back and forth above the ironing board. This experiment with Viki would inspire other researchers to conduct similar experiments. But when it came to teaching Viki to speak, the Hayes' efforts were only marginally more effective than others who tried to teach chimps to talk. After nearly seven years of intensive exposure to English, Viki spoke only four words, mama, papa, cup, and up.
1960s–1980s: Sign language Washoe and the Gardners
In 1966, the husband-and-wife research team of Beatrix T. Gardner and Robert Allen Gardner initiated a new generation of language research. After the failed efforts of teaching apes to speak, the Gardners wondered whether the issue was a motor deficiency rather than cognitive inability. The couple had been watching film of Viki, the chimp involved in the early speech study, and noticed that she was intelligible without sound; she was making gestures with her hands as she tried to pronounce words. The Gardners decided to test a chimpanzee's abilities with a gestural language, American Sign Language (ASL). They were not the first scientists to come up with this idea. Pepys advocated teaching sign language to chimps in the 17th century; de la Mettrie and Monboddo suggested the same in the 18th; and William Wundt in the early 20th century. But the Gardners were the first to conduct formal research into the matter.
The Gardners secured a 10-month-old chimpanzee they named Washoe in June 1966. Up to age 5, Washoe lived in a trailer in the backyard of the Gardner's home in Reno, Nevada. The Gardners hired graduate students to work with Washoe, most notably Roger Fouts, who later became Washoe's primary caregiver. No one around Washoe was allowed to speak; instead, they were instructed to use signs from American Sign Language (ASL) exclusively. Washoe's primary caregivers were not fluent in ASL. The Gardners employed native ASL speakers on subsequent chimp projects.
The Gardners tried to anticipate criticism of their work from the start. A word would not be counted as part of Washoe's vocabulary until she had used it appropriately and spontaneously at least once a day for 15 consecutive days. (Penny Patterson used this framework for her studies with gorilla Koko as well, at least initially.Patterson (1981)) It proved to be a difficult benchmark to meet, especially when it came to the vocabulary involving things not typically encountered daily (horse, pipe, hankie).
In addition, the Gardners set up a double-blind testing apparatus for Washoe and subsequent chimp language projects. The chimp was seated in front of a screen that was sheltered from human view. One person would flash random slides for the ape to see, another person (who could not see the slides) would record the ape's response, and a third person viewing from a one-way mirror in a separate room would independently record the chimp's response. Two persons were employed to separately interpret Washoe because of the inherent ambiguity of reading an ape's signs: chimp hands and body are different than humans', and the meaning of ASL signs is shaped by their position and movement in space regarding one's body. When the two interpretations were found to match each other as well as the picture that had been shown, the sign was accepted as correct. Anything else was recorded as an error. (In his book, Next of Kin, Roger Fouts wrote that he sometimes found the errors more illuminating than correct responses.)
The double-blind testing apparatus was set up to avoid unconscious bias, particularly a Clever Hans effect, in which humans unwittingly tip off their animal subjects through body language, facial expressions, or other means.
Tests showed Washoe reliably used 85 signs singly and in combination with other words by her third year with the Gardners. (The number of reliable signs rose to 132 later.). According to Eugene Linden, an independent journalist who focused on ape language research, she asked questions and used negatives ("no" in combination with another word).Linden, E. (1986) p. 21
When Washoe was five, the Gardners arranged to send her to the University of Oklahoma's Institute of Primate Studies in Norman, Oklahoma, with Roger Fouts and Deborah Fouts. The Gardners continued to conduct sign-language research on infant chimpanzees, using Moja, Pili, Tatu, and Dar in subsequent studies. With these later projects, the couple sought to improve on the methodology of Project Washoe by securing chimps immediately after birth, employing fluent ASL speakers, providing the chimps with chimp "siblings"; and iterating upon their language training techniques.Fouts (1997), pp. 202–203.
Washoe and Roger Fouts
The Gardners were scientists schooled in behaviorism. Roger Fouts came to the chimp language studies as an animal lover pursuing a career in child development. These differing backgrounds corresponded with differing approaches. The Gardners initially wanted Fouts and other grad students to strictly use methods of operant conditioning – rewards and punishment – to teach Washoe, but Fouts believed that teaching a language was not the same as teaching a lab rat tricks. He recalled: According to behaviorism, the combination of a hungry chimp and ready-to-dispense food should be the perfect opportunity for reinforcement and learning. But the hungrier Washoe was, the quicker her signing deteriorated into pure repetition and finally outright begging.Fouts, R. (1997), p 83.Fouts believed that chimpanzees needed room to learn in manner similar to human children, on their own timeline. He considered direct instruction ineffective, as it was often met with resistance. The child, not the parent, drives the learning process, argued Fouts:If you try to impose a rigid discipline while teaching a child or a chimp, you are working against the boundless curiosity and need for relaxed play that make learning possible.Though the Gardners instituted Skinnerian protocols in Washoe's first year, they began to see advantages to Fouts' approach, acknowledging, "Young chimpanzees and young children have a limited tolerance for school." But the issue exposed a key tension behind Project Washoe and similar language research to follow. On one hand, researchers needed a strict, repetitive process with clinical double-blind testing for their work to be accepted as science. Without such rigor, the body of work became vulnerable to criticism. On the other hand, researchers need to recognize the apes' emotional needs or they faced a different suite of problems. The Gardners fit more comfortably in the first camp, focused on scientific rigor; Roger Fouts and his wife Deborah fit more in the latter, later becoming advocates for animal rights and welfare. But the tension proved unavoidable.
Nim Chimpsky
In 1973, Herbert S. Terrace of Columbia University set out to improve upon the Washoe research using a chimp he named Nim Chimpsky (a pun on linguist Noam Chomsky). Over the course of Project Nim, the infant chimp was shuttled between locations and a revolving group of roughly 60 caregivers, mostly students and volunteers, few of whom were proficient in sign language.
Before he was 1 year old, Nim began fighting for dominance by biting his caregivers.Hess, E. (2008) p. 89. See also Project Nim (2011) documentary. The project was initially intended to last roughly 10 years.Hess, E. (2008) p. 75 But after four years of research, Nim had become too difficult to manage and was returned to the Institute for Primate Studies in Oklahoma.
Nim's chaotic upbringing, documented in Elizabeth Hess's biography Nim Chimpsky: The Chimp Who Would Be Human, negatively impacted not only his behavior but his performance on language-related tasks. Even Terrace acknowledged this problem, noting that Nim's "emotional turmoil" was a "major obstacle" in his progress.Terrace, H. (1979) p. 221. See also Linden, E. (1986), pp. 71–72