Although an almost bewildering number of sophisticated instructional aids-from computers to tutors-exist today, perhaps the oldest, most ubiquitous, and least understood is language.
The use of language for instructing begins at an early age, in the child's home, and its use multiplies and compounds during schooling until, at the University, students are engulfed in a four-year "swarm" of oral and written language units-which Rothkopf has estimated may approach 6 million to 12 million words! (1972, p. 316)
Students in Universities are not the only ones who encounter formidable linguistic "swarms" - in their education. In 1965, some 2,935,000 students were enrolled in correspondence courses; 1,767,400 of them were Armed Forces personnel (MacKenzie, Christensen and Rigby, 1968, p. 7). For these students, the written language is the primary instructional tool. No one knows how many oral language units the Armed Forces and other organizations use in their instructional programs, but the lecture method, along with many reading assignments, still dominates the scene.
Even in innovative instructional systems, such as the Air Force's computer-based Advanced Instructional System (AIS) concept, a great deal of instruction consists of oral and written language. Most computer displays-like most educational films, film strips, or illustrations-are unable to present concepts, especially abstract concepts, without oral or written language.
Many non-hardware based instructional innovations, such as peer instruction, role playing, and T-groups, also seem to rely heavily on language for their effectiveness although, in such practices, the relative contributions of linguistic and non-linguistic affective factors to the achievement of the educational objectives are unknown.
It seems clear that, because of the central role language plays in instruction and learning, there is a need for as complete and sound an understanding as possible of (a) how people learn their various language competencies and (b) how they gain knowledge by use of these competencies (cf., Carroll, 1968).