Nature of phonological delay in children with specific language impairment

This study investigated the nature of phonological delay in a group of children with specific language impairment. It was asked whether phonological errors in this group of children were generated by a slow but normal language learning process or whether they reflected a selective impairment in some representations that enhance normal acquisition and use of a language phonology. A group of 10 children with SLI (mean age = 5.1) was compared with three groups of normal children who were matched in age (age control group, mean age = 5.1), in sentence comprehension and recalling (grammar control group, mean age = 3.7), or who exhibited a phonological performance lower than the age average (group with low phonological performance, mean age = 4.4). The four groups of children were assessed in terms of: (1) responses to a mispronunciation detection task; and (2) error profiles with complex and simple syllabic structures. Performance on the mispronunciation detection task showed that the group with SLI could distinguish a target lexical item from acoustic non-word stimuli that were highly similar to it in terms of phonetic characteristics. An analysis of overall error rate at this task showed, however, that four children with SLI had a much lower performance than normal children of the same age, even when the auditory stimuli were tokens of the target word, or non-words that were phonetically different from the target. A difficulty in coordinating vocal actions in an articulatory plan accounted for error profiles with simple syllabic structures both for some children with SLI and normal children with phonological performance lower than the age average. A severe difficulty with representing complex syllabic structures was a homogeneous characteristic of the group with SLI and worked as the main indicator of impaired, rather than simply slow, phonological development.