development (r = 0.56, p < 0.05). This difference may be due to sample differences; Cross' sample consisted of children known to be rapid acquirers.

Henzl (1973) reports that teacher-talk is better formed than native speaker-native speaker speech. This was confirmed by Wiley (1978), who also found some signs of tuning: her beginning ESL students heard fewer disfluencies than did intermediate and advanced students. Freed (1980) reported that in her study of Americans talking to ESL performers, foreigner-talk appeared to be about as well formed as caretaker speech (compared to Newport, 1976). There are no data for interlanguage-talk, which is probably not as well formed as native speaker-native speaker speech.

4. Length. Caretaker speech is shorter than adult-adult speech but, as Newport et al. point out, this does not necessarily mean simpler. As seen in Table 1, Cross (1977) finds evidence for at least rough tuning, but Newport et al. do not. As mentioned above, this may be due to sample differences. Henzl confirms that teacher-talk is shorter than native speaker-native speaker speech, but did not search for tuning. Again, there are no data for interlanguage-talk and foreigner-talk.

5. Propositional complexity. As seen in Table 1, there is some evidence for rough tuning in caretaker speech for this feature: there are generally positive correlations (but not usually significant) between the number of S nodes per utterance in the input and the child's linguistic maturity, again with higher correlations found in Cross' study. Trager (1978) used this measure for input to second language acquirers, finding again that teacher-talk is less complex than native speaker-native speaker talk, and also that beginners received somewhat less complex input than intermediate and advanced students.

Other scholars have used other measures. Both Gaies (1977) and Wiley (1978) used T-unit-based measures, such as words per T-unit and clauses per T-unit. Briefly, both studies agree that teacher-talk is simpler than native speaker-native speaker speech. Gaies, however, found evidence for tuning by level, his beginners receiving simpler input than his intermediates, and his intermediates receiving simpler input than his advanced ESL students. Wiley, with a slightly smaller sample, did not find evidence for tuning by level. Henzl also reports less subordination in teacher-talk.

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