The influences of behavioristic psychology and descriptive linguistics were at their peak from World War I to shortly after World War II, when the foundations of the audio-lingual approach were being laid. In addition, the field of descriptive linguistics was profoundly affected by the theories of learning held by the behavioristic psychologists. Learning, as was stated earlier, was viewed basically as being a process of conditioning behavior. From this tenet came the definition of learning as "a change in behavior." Brooks (1964, p. 46), for example, defines learning as "a change in performance that occurs under the conditions of practice/'
Language, although more complex, was no different from any other learning. Language, too, was composed of conditioned responses. Skinner (1957, p. 81) makes quite clear that language is no different from other learned behavior when he says:
In all verbal behavior under stimulus control there are three important events to be taken into account: a stimulus, a response, and a reinforcement. These are contingent upon each other, as we have seen, in the following way: the stimulus, acting prior to the emission of the response, sets the occasion upon which the response is likely to be reinforced. Under this contingency, through a process of operant discrimination, the stimulus becomes the occasion upon which the response is likely to be emitted.
Other psychologists agree with Skinner. Broudy and Freel (1956, p. 86) summarize their feelings as follows:
More complicated behaviors, including the learning of language meanings, also are described by conditioning. Thus, according to Mowrer, the meaning of a predicate is transferred by conditioning to the meaning of a subject. For example, the meaning "thief" is attached to the meaning "Tom" in the sentence "Tom is a thief."
These same tenets have also been accepted as valid in second-language learning. Morton and Lane (1961) concluded on the basis of laboratory experiments that the tasks involved in learning another language are "indistinguishable" from those required to condition desired behavior in the animal laboratory. In addition, Lane (1964, p. 250) has stated, "there is nothing extrapolative in the application of laboratory techniques and nothing metaphorical in the use of concepts gained from a functional analysis of behavior in the laboratory."