Effects of general processing capacity and sustained selective attention on temporal processing performance of children with specific language impairment

Extract

This study investigated the potential influences of general processing capacity and sustained selective attention on the temporal processing of a group of children with specific language impairment (SLI) and a group of age-matched (CA) controls. Children completed a sustained selective auditory attention task and two speech processing tasks, the Speech Identification Task, representing a cognitively more complex task, and a standard speech discrimination task, representing a cognitively less complex task. The speech stimuli included two-formant, 40-ms transition [ba] and [da] consonant–vowel (CV) syllables and the nonstop CV syllable [sa]. We hypothesized, in accordance with Tallal's temporal processing deficit view, that if SLI children have a fundamental deficit in temporal processing, they should demonstrate poor performance on both speech processing tasks relative to CA children. By contrast, if the temporal processing problem of SLI children relates to a limitation in general processing capacity, the SLI children should show better performance on the discrimination task compared to the identification task. Alternatively, if poor sustained selective attention mediates SLI children's poor temporal processing, the SLI children should show poor performance on an independent measure of auditory attention, which in turn should account for a portion of the variance in any observed group differences in temporal processing. Results showed no group difference in sustained selective auditory attention. On the identification task, group, stimulus-type, and interaction effects emerged. SLI children performed more poorly than CA children, and stop CV syllables were identified less frequently than the nonstop CV syllable. On the discrimination task, there were no main effects or interactions for accuracy (Á score). For the reaction time analysis, only a stimulus-type effect was found, with children responding faster to the /sa/ syllable. Results were interpreted to suggest that these SLI children did not evidence a basic temporal processing deficit. Rather, the SLI children's poor identification task performance was interpreted to reflect an interaction between these children's more limited general processing capacity and the nature of the task.