304 | Great Apes and Language Research to talk These yielded very little success, and their failure has been attributed to anatomical differences in the vocal tracts of nonhuman great apes and humans All of this changed in 1966, when Allen and Beatrice Gardner pioneered the teaching of American Sign Language (ASL) to the chimpanzee Washoe When Washoe was four years old, the Gardners reported that she had reliably acquired at least 132 ASL signs As they wanted to exclude the risk of inadvertent cueing, the Gardners tested Washoe and other ASL chimpanzees individually, requiring them to name objects shown on slides Two uninformed observers recorded their signs The chimpanzees usually provided more than 80 percent correct responses, and inter-observer agreement was around 90 percent (Gardner & Gardner, 1969; Gardner & Gardner, 1989) In the 1970s, Project Washoe was taken over by Roger and Debbie Fouts Similar ASL projects were started with other great apes, such as the gorilla Koko by Francine Patterson, the chimpanzee Nim by Herbert Terrace, and the orangutan Chantek by Lyn Miles Different communication methods were used as well David and Ann Premack taught the chimpanzee Sarah to communicate by means of plastic symbols, and Sue Savage-Rumbaugh uses a computer console with arbitrarily designed geometric forms or lexigrams for her research with the bonobo Kanzi and other great apes In particular, toward the end of the 1970s, ape language research came under heavy fire The single most significant blow was provided by psychologist Herbert Terrace of Columbia University Terrace came to question his former research with the chimpanzee Nim after analyzing videotapes of Nim and his teachers In an article published in 1979 in Science, Terrace and his colleagues wrote that the majority of Nim’s utterances (87 percent) immediately followed a human’s utterance or so-called adjacent utterances Also, nearly 40 percent of these utterances were classified as partial imitations of what the human teacher had signed (Terrace et al., 1979) However, what remained an unfortunate blind spot in the article was the fact that the majority of Nim’s utterances were either spontaneously initiated by Nim (13 percent) or composed of novel signs (40.6 percent), signs that differed from those used by the human teacher It is also important to take into account the highly controlled training conditions and Nim’s increasingly problematic psychological state Nim was taught sign language for five to six hours a day in a concrete classroom of barely six square meters Terrace later “wondered how I and the other teachers could have spent so much time in these oppressive rooms.” (Terrace 1979, 1987, p 209) Though chimpanzees develop strong social bonds that may last a lifetime, Nim had some sixty teachers within only four years Even his eight principal caregivers were present for only parts of these four years, and Terrace was too busy with many other occupations to be present enough for Nim’s developmental wellbeing Al four of Nim’s main caregivers at the Delafield house left around August and September 1976 In particular, when Laura Petito left, Nim became depressed and inconsolable (Terrace 1979, 1987, p 108) Terrace recognized that “undoubtedly the loss of Nim’s immediate family at Delafield at a critical stage of his growth had a permanent adverse effect on his social, linguistic, and emotional development” (Terrace 1979, 1987, p 139) Nevertheless, at least four