As detailed in Chapter II, speech production can come from any of three different sources. First, we can use our acquired competence as illustrated in the Monitor model for production in Chapter II. According to the input hypothesis, this sort of production takes some time to develop. Another way is via memorized patterns and routines (see Krashen and Scarcella, 1978). A third way is by extensive use of first language structures, as explained n Chapter II. The latter two methods of speech production are ways of "performing without competence" (borrowing R. Clark's terminology). A second language performer can "learn to speak" very quickly using these methods, and they are explicitly encouraged by some techniques. They are severely limited modes, however. (See discussion in Chapter II, Krashen and Scarcella, 1978, and Krashen 1981.)

This raises the interesting question of whether participation in conversation is even practically necessary for truly successful second language acquisition. It probably is. In addition to being an effective means of obtaining comprehensible input, conversation offers some other real advantages that will become clearer as we proceed in this chapter. Scarcella (forthcoming) points out that there are many aspects of "communicative competence" that are probably not acquirable by observation and input alone (see discussion later in this chapter). Also, Scarcella points out that real conversation entails "a high degree of personal involvement", what Stevick (1976) terms "depth" and a lowered affective filter.

In a review of the science fiction literature, Hatch (1976) points out several examples in which authors assume that it is possible to acquire human language by listening to radio broadcasts. Even these authors seem to understand, however, that acquiring language by listening to incomprehensible input is an ability possessed only by certain aliens with different, and apparently superior "language acquisition devices".

There are anecdotal cases of people who have picked up second languages via television. Larsen-Freeman (1979), for example, cited a case of a German speaker who acquired Dutch via TV. This is not at all strange, as much input in Dutch would be comprehensible to a speaker of such a closely related language. Note that I am not claiming that it is impossible to acquire language from TV. I am only saying that comprehensible input is necessary for acquisition and that television provides little comprehensible input for a beginner. Intermediate level students may profit quite a bit from television and even radio.

Another way teachers help students understand messages containing structures that are "beyond" them is by emphasizing vocabulary. Both Evelyn Hatch and I have stated the argument for increased vocabulary work in recent years (Hatch, 1978a; Krashen, 1981), and our argumentation is, I think, similar. While knowledge of vocabulary may not be sufficient for understanding all messages, there is little doubt that an increased vocabulary helps the acquirer understand more of what is heard or read (see e.g. Ulijn and Kempen, 1976; Macha, 1979, on the role of vocabulary in reading comprehension). Thus, more vocabulary should mean more comprehension of input, and more acquisition of grammar. This "new view" is quite different from earlier positions. Language teachers had been told to restrict introduction of new vocabulary in order to focus on syntax. Now we are saying that vocabulary learning will actually contribute to the acquisition of syntax.

The practical implications of this position are not clear to me, however. Should we teach vocabulary in isolation in an effort to boost the amount of input that is comprehensible? Unfortunately, there is little research that speaks directly to the question of how