The use of intermediary gesture languages to speak with primates

Anthropoids’ can freely and fast move their hands, and sign language became the next obvious choice in the development of direct dialog between humans and other species. Ulanova (1950) possibly was the first who taught a primate to use gesture signs to denote desired things (Fig. IX-1). She taught a rhesus macaque to make finger gestures in order to obtain rewards of different kinds. Different gestures corresponded to different food items (nuts, pieces of apples, bread, strawberry, garden radish) and drinks (coffee, tea, and milk). A monkey was firstly taught to extend its hands to a human tutor and then the tutor moulded its hands and fingers to the right position and reinforced correct signs. It took from 152 to 576 trials to shape each gesture sign. The most accuracy was achieved with the use of signs “bread” and “apple”.

Several projects trying to teach apes developed human language started in 1966, from the project of R.A. and B.T. Gardners who began teaching a chimpanzee Washoe the use of American Sign Language (ASL or AMESLAN), a gestural form of communication used by deaf people. Gardners based their experiments on cross fostering paradigm that includes treating the chimpanzee infant like a human child in all living arrangements, 24 hours a day, every day of a year. The same paradigm has been applied later in other projects connected with teaching apes different forms of language.

Using ASL, Gardners followed the parents of deaf children by using an especially simple and repetitious register of ASL and by making signs on the youngster’s bodies to capture their attention. The people who cared for and taught Washoe used sign language almost exclusively in her presence. The performance of Washoe can be compared with that of deaf children. Fascinating results of this project are described in papers and books of Gardners (Gardner and Gardner, 1969, 1980, 1998) and in Linden’s (1974) popular book “Apes, Men and Language”.

Washoe learned signs slowly at first but after four years of training she could use about 160 signs that included nouns, verbs, and pronouns. Washoe was able to transfer her signs spontaneously to a new member of a class of referents; for example, she used the word " more" in a wide variety of contexts (not just for more tickling, which was the first referent); she also used “open" with doors, tins and nuts. She was able to use combination of signs, starting with two signs and then progressing to four- or five- sign “sentences”, for instance, “give me tickle”, “open food drink” (meaning “open the fridge”). One famous example is the novel sequence “baby in my drink” which was produced in response to being shown her cup with a doll in it. Gardners (1975) noted that Washoe used the “dog” sign as a reaction to the sound of barking by an unseen dog. They also reported that Washoe began to use combinations of signs spontaneously after learning only about eight or ten of them. She thus has invented " new" words: once she was signing " Water" - " Bird" when she saw a swan for the first time.

Some years after the start of the study (and after the death of her own baby) Washoe adopted an infant chimpanzee called Loulis in whose presence no human would use any signs. Despite this he had a repertoire of about 50 signs after five years. Some of these were learned by imitating Washoe and other signing apes in the research centre, but there was also evidence that Washoe moulded his hands into the correct position (Fouts et al., 1982). She succeeded to teach Loulis at least two words: “food” and “chair”. This seems to be an evidence of cultural transmission. The development of many phrase types with three signs was recorded for Loulis. An example is “hurry you tickle”.

Gardners soon extended their experiments to several other chimpanzees. All of them were born in American laboratories and each was included into cross-fostering experiment within a few days of birth. Young chimpanzees were raised in an environment of people who communicated by ASL between themselves and with chimpanzees. As a result, chimpanzees purposely signed to friends and to strangers; they signed to each other and to themselves, to dogs and to cats, toys, tools, even to trees. Because the chimpanzees continued to use sign language without any input from humans, Gardners concluded that once introduced, sign language is robust and self-supporting (Gardner and Gardner, 1989).

Another chimpanzee who was systematically taught sign language was Nim. This chimpanzee was educated by Terrace who was skeptical about linguistic success of apes. Terrace believed that there were simpler explanations for many of the reported interpretations of these apes' language use. Although Terrace admitted that the apes had achieved something significant, he compared their behaviour to that of pigeons that are taught to peck different colours in a certain order (Terrace 1979). He also believed that the apes used signs only to receive rewards from their human trainers. When Terrace set up his own experiment with Nim, he found some exciting and important details in chimpanzee’s way to use language. Nim learned 125 signs, and a record of over 19000 utterances he made was kept. Nim was observed practicing his signs in the absence of their referents (Terrace, 1979). He often signed “dirty” when he had to go to the toilet or “sleep” when he was bored and wanted a change. He used the signs “bite” and “angry” to express his feelings, and he tended not to attack if he perceived that his warning was heeded; this is an important substitution of an arbitrary word for a physical action, displaying Hockett's property of specialization (the speaker does not act out messages).

However, Terrace found little evidence of Nim showing any ability to use language. When using more than two signs Nim showed no evidence of use of grammar and he could not combine words to create new meanings on his own. Detailed analysis of video records showed that Nim interrupted his trainers more than human children interrupt their parents. Besides, a part of imitation among utterances produced by Nim increased with age whereas in children inverse negative relationship takes place. Terrace suggested that if we are going to say that apes can create a sentence, we must eliminate the other possible explanations for the utterances. Terrace is not as much of a skeptic as some others make him out to be, though; he believes that the conditions under which Project Nim was operated were not ideal, and future projects might have more success if they were able to instil a greater motivation to sign in their subjects.

The starting projects stimulated interest in “speaking apes”. Fouts spent several years educating young chimpanzees raised in laboratories or adopted by families. He found a great individual variability in apes’ motivation and capability and discovered interesting abilities in some of them. For example the chimpanzee Elli was shown to be able to “translate” nouns from English to ASL by herself, and Fouts proved this by special experiments (Fouts, 1997).

Similar studies using ASL were carried out using gorillas and an orangutan. Koko is a female gorilla who has been trained by Paterson at Stanford University in California. Koko has a working vocabulary of over 500 signs and has emitted over 400 more (Patterson, 1978, 1981; Patterson et al., 1988). Koko uses more words per utterance on average that Nim did, and a great deal of creativity, spontaneity, and structure characterize her utterances. She also rhymes and jokes; on one occasion she used a metaphor of an elephant to refer to herself when she pretended a long tube was her " trunk”. She also signed “white tiger” to refer to a zebra, “eye hat” for mask, “cookie rock” for sweet, “state roll”, and “elephant baby” when shown to a Pinocchio doll. These characteristics of Koko's utterances show the property of productivity, in which a speaker says something never heard or said before and is understood by the audience. She signed “me cry there” when she saw a picture of a gorilla in a bath, apparently a cry of sympathy, since she herself hates being bathed. In a fury, she once signed “Penny toilet dirty devil” when she was angry with Penny Paterson, her trainer. Being hot tempered but noble-minded, Koko apologised for a biting incident. When shown a bite mark on Penny’s arm she signed “sorry bite scratch wrong bite”. “Why bite” queried Penny. “Because mad”, Koko replied. “Why mad? ” asked Penny. “Don’t know “responded the gorilla. Koko was later joined with another gorilla, Michael (also educated by ASL), and demonstrated the “displacement” feature of her language by referring to him when he was not present. Chantek, an orangutan, learned about 150 different signs, and used them spontaneously and without undue repetition. Chantek internalized the minimal value system, using signs for “good”and “bad”in appropriate contexts (Miles, 1993, 1994).