Untrained acquisition of /s/ in a phonologically disordered child.

The untrained /s/ productions of a phonologically disordered child were followed over a period of several months as she produced /s/ in imitated words and in spontaneous connected speech. For this child, as has been reported in the literature for children acquiring phonology normally, /s/ occurred earliest in the word-final position, appearing in word-initial position only several weeks later. Two word-medial, or intervocalic, contexts were compared: (a) monomorphemic words in which /s/ is word- and morpheme-medial (e.g., lasso); and (b) bimorphemic words in which /s/ is word-medial but morpheme-final (e.g., missing). In this latter group, a grammatical inflection or morpheme was added to a morpheme that ends with /s/. Correct responses to the intervocalic position where /s/ occurred at a morpheme boundary (i.e., in inflected morphemes) occurred earlier and more frequently than responses to single-morpheme intervocalic position. The variability of the child's productions over time is examined and discussed.