Theorists place different values on the role of interaction in second language acquisition (SLA). Krashen’s (1985, 1994) theory became a predominant influence in both second language teaching practice and later theories. Krashen postulates that SLA is determined by the amount of comprehensible input, that is, one-way input in the second language that is both understandable and at the level just beyond the current linguistic competence of learners. Similar to Vygotsky’s “zone of proximal development” (1962), Krashen’s scaffolding theory is referred to as i+1.
Viewed as an innatist perspective, this theory maintains that a second language is acquired unconsciously in a manner similar to the acquisition of a first language. According to Krashen (1996), acquiring language is predicated upon the concept of receiving messages learners can understand (1996). Teachers can make language input comprehensible through a variety of strategies, such as linguistic simplification, and the use of realia, visuals, pictures, graphic organizers, and other current ESOL strategies.
While Krashen (1994) believes that only one-way comprehensible input is required for SLA, others take an interactionist position acknowledging the role of two-way communication. Pica (1994), Long (1985), and others assert that conversational interaction facilitates SLA under certain conditions. According to Lightbrown and Spada (1999), “When learners are given the opportunity to engage in meaningful activities they are compelled to ‘negotiate for meaning,’ that is, to express and clarify their intentions, thoughts, opinions, etc. in a way which permits them to arrive at a mutual understanding. This is especially true when the learners are working together to accomplish a particular goal . . . “(p. 122). Pica (1994) goes on to say that negotiation is defined as “modification and restructuring that occurs when learners and their interlocutors anticipate, perceive, or experience difficulties in message comprehensibility” (p. 495).
A variety of modifications, which may involve linguistic simplification as well as conversational modifications such as repetition, clarification, and conformation checks, may be used to gain understanding. The interaction hypothesis of Long and Robinson (as cited in Blake, 2000) suggests that when meaning is negotiated, input comprehensibility is usually increased and learners tend to focus on salient linguistic features. Cognizance of these language forms and structures is seen as beneficial to SLA. Other nteractionist theorists apply Vygotsky’s socio-cultural theory of human mental processing to define the role of interaction in SLA (Lightbrown and Spada, 1999) and hypothesize that second language learners gain proficiency when they interact with more advanced speakers of the language, for example, teachers and peers. Scaffolding structures such as modeling, repetition, and linguistic simplification used by more proficient speakers are believed to provide support to learners, thus enabling them to function within their zones of proximal development (Vygotsky, 1962).
Although theorists adhering to interactionist thought consider both input to, and input from, the learner as important, output is often viewed as secondary. However, Swain (1995) in her “comprehensible output hypothesis” asserts that output is also critical and hypothesizes that it serves four primary functions in SLA: 1) enhances fluency; 2) creates awareness of language knowledge gaps; 3) provides opportunities to experiment with language forms and structures; and 4) obtains feedback from others about language use.
Comprehensible output assists learners in conveying meaning while providing linguistic challenges; that is, “. . . in producing the L2 (the second, or target language), a learner will on occasion become aware of (i. e. , notice) a linguistic problem (brought to his/ her attention either by external feedback or internal feedback). Noticing a problem ‘pushes’ the learner to modify his/ her output. In doing so, the learner may sometimes be forced into a more syntactic processing mode than might occur in comprehension” (Swain and Lapkin in Chapelle, 1997, p. b). From this perspective, comprehensible output plays an important role in interaction. In summary, interactionists elaborate upon the innatist notion of comprehensible input explaining that interaction, constructed via exchanges of comprehensible input and output, has at least an enhancing effect when meaning is negotiated and support structures are used. Based on this premise, distance second language learning courses should be designed to provide interaction that includes negotiation of meaning where comprehensible output results from input.