On the basis of his work with another chimpanzee called Nim, the psychologist Herbert Terrace argued that chimpanzees simply produce signs in response to the demands of people and tend to repeat signs those people use, yet they are treated (by naive researchers) as if they are taking part in a “conversation.” As in many critical studies of animal learning, the chimpanzees’ behavior is viewed as a type of conditioned response to cues provided (often unwittingly) by human trainers. Herbert’s conclusion was that chimpanzees are clever creatures who learn to produce a certain type of behavior (signing or symbol selection) in order to get rewards and are essentially performing sophisticated “tricks.”

In response, the Gardners argued that they were not animal trainers, nor were they inculcating and then eliciting conditioned responses from Washoe. In complex Figure 2.3 18 The Study of Language experiments, designed to eliminate any possible provision of cues by humans, they showed that in the absence of any human, Washoe could produce correct signs to identify objects in pictures. They also emphasize a major difference between the experiences of Washoe and Nim. While Nim was kept in a windowless cell as a research animal and had to deal with a lot of different research assistants who were often not fluent in American Sign Language, Washoe lived in a domestic environment with a lot of opportunity for imaginative play and interaction with fluent signers who were also using sign language with each other. They also report that another group of younger chimpanzees not only learned sign language, but also occasionally used signs with each other and with Washoe, even when there were no humans present.