Role of phonotactic frequency in nonword repetition by children with specific language impairments

Children with specific language impairments (SLI) repeat nonwords less accurately than typically developing children, suggesting a phonological deficit. Much work has attempted to explain these results in terms of a phonological memory deficit. However, subsequent work revealed that these results might be explained better as a deficit in phonological sensitivity.

This study used a nonword repetition task to examine how children with SLI extract phonological regularities from their language input.

Eighteen English-speaking children with SLI (7;3-10;6) and 18 age-matched controls participated in two English nonword repetition tasks. Three- and four-syllable nonwords varied in a single phonotactic frequency manipulation, either consonant frequency or phoneme co-occurrence frequency, while all other factors were held constant. Repetitions were scored in terms of accuracy as either the percentage of phonemes correctly produced or phoneme co-occurrences (diphones) correctly produced. In addition, onset-to-onset reaction times and repetition durations were measured.

Accuracy results revealed significant group, length, and phonotactic frequency effects. Children with SLI repeated nonwords less accurately than age-matched peers, and all children repeated three-syllable nonwords and those with higher frequency phonotactic patterns more accurately. However, phonotactic frequency by group interactions were not significant. Timing results were mixed, with group reaction time differences for co-occurrence frequency, but not consonant frequency, and no group repetition duration differences.

While children with SLI were less accurate overall, non-significant interactions indicate that both groups of children were comparably affected by differences in consonant and diphone frequency.