LANGUAGE PROCESSING ABILITIES OF NORMAL AND SPECIFICALLY LANGUAGE IMPAIRED CHILDREN

Evidence has accumulated which indicates that children with Specific Language Impairments (SLI) display acoustic-perceptual deficits as well as linguistic-conceptual difficulties. This research investigated how lower-levels of phonetic encoding and higher-levels of linguistic and contextual knowledge interact in the processing of language of SLI and normal children. The objectives of this investigation were: (1) to describe the differences in the language processing abilities of SLI and normal children, (2) to study the effect of age on the processing abilities of these two groups, and (3) to evaluate whether these children are able to use a pictorial cue to predict sentence meaning.

Thirty SLI children and thirty-five normal language learning children between $3{1\over2}$ and $8{1\over2}$ years of age served as subjects. Minimally contrastive speech pairs, varying in complexity from CV syllables to complex sentences and describing events which were more or less likely to occur in real life, were presented. The children's task was to identify each stimulus by pressing a computer paddle associated with a card or picture, as quickly as possible. The speech was presented as natural stimuli (Study 1) and degraded by a white noise (Study 2). In Study 3, an additional contextual cue was provided as the children identified the degraded sentences.

The principle findings were that the SLI children were generally less accurate and slower than the normal children in processing all types of speech stimuli. Both populations showed a general improvement in accuracy and a decrease in response latency with increasing age. The relative patterns of accuracy and latency were similar for the two subject groups. The linguistic/contextual predictability of the stimuli influenced the performance of the SLI and normal children differently, in both the natural and degraded conditions. The SLI children did not show a significant benefit in their responses with the addition of a contextual cue, unlike the normal children who were able to apply the cue information to benefit their responses.

The results were discussed with respect to the children's use of acoustic-phonetic encoding and linguistic/contextual knowledge in language processing. Clinical implications for the treatment of SLI children were presented.