The current status of the motherese hypothesis.

Partially conflicting results from correlational studies of maternal speech style and its effects on child language learning motivate a comparative discussion of Newport, Gleitrnan & Gleitman (1977) and Furrow, Nelson & Benedict (1979), and a reanalysis of the original Newport et al. data. In the current analysis the data are from two groups of children equated for age, in response to the methodological questions raised by Furrow et al.; but, in line with the original Newport et al. analysis, linguistic differences between these age-equated children are handledby partial correlation. Under this new analysis the original results reported by Newport et al. are reproduced. In addition, however, most effects of the mother on the child's language growth are found to be restricted to a very young age group. Moreover, the new analysis suggests that increased complexity of maternal speech is positively correlated with child language growth in this age range. The findings are discussed in terms of a theoretical analysis of the Motherese Hypothesis; the [.] This research was supported in part by a grant to L. R. Gleitman and B. Landau from the National Foundation for the March of Dimes; by grants NS 16878 and BNS-80-13509 to E. L. Newport and T. Sup alia from the National Institutes of Health and the National Science Foundation, respectively; and by grant HD 05951 to J. Campione and A. Brown from the National Institutes of Health. We thank Adele Abrahamsen, Jon Baron, D. Crystal, Barbara Landau, Richard Meier, Steve Pinker, Marilyn Shatz, Scott Weinstein and an anonymous reviewer for helpful comments on an earlier draft of this paper, and Jim Morgan, for computer expertise in analyses of the data. Address for correspondence: Lila Gleitman, Department of Psychology, University of Pennsylvania, 3815 Walnut Street, Philadelphia, Pa, 19104, USA.