Critical periods and SLI

After summarizing the main points of Jurgen M. Meisel's paper in this issue of Zeitschrift fur Sprachwissenschaft that supports Robert Bley-Vroman's (1990 & to appear) fundamental difference hypothesis (FDH) & finding his argumentation "clear & convincing," three issues for further discussion & investigation are identified: (1) second language acquisition in a sub-optimal setting, (2) how do children learning a second language, with the age of onset of acquisition between four & seven, manage to achieve native competence despite their changed language making capacity (LMC) & language acquisition device (LAD)? & (3) what role does transfer play in child second language learning? Moreover, it is observed that Meisel's proposal with explicit fixing of at least two of the transition points in the domain of grammar at ages four & six to seven are also highly relevant to the research on children with impaired language acquisition, in particular the grammar SLI (specifically language impaired) subpopulation. Some proposals are made on how the study of successive language acquisition in children, the critical period hypothesis, & the FDH in particular, & Meisel's claims might help to widen the discussion on grammatical SLI, including assessment & therapy aspects. Z. Dubiel