Lexicality and frequency in specific language impairment: accuracy and error data from two nonword repetition tests

Area of Science:

• Linguistics
• Developmental Psychology
• Speech and Language Pathology

Background:

• Specific language impairment (SLI) is often linked to deficits in phonological working memory or phonological processing.
• Understanding the underlying mechanisms of SLI is crucial for effective intervention strategies.
• Nonword repetition tasks are valuable tools for assessing phonological skills in children.

Purpose of the Study:

• To differentiate between phonological working memory and phonological processing deficits as explanations for SLI.
• To investigate the role of lexicality and phonotactic frequency in nonword repetition in children with SLI.
• To compare the nonword repetition performance of children with SLI and typically developing (TD) children.

Main Methods:

• Eighteen children with SLI and 18 TD children participated in the study.
• Participants completed language and nonverbal intelligence assessments.
• Two nonword repetition tests, varying in lexicality and frequency, were administered.

Main Results:

• Children with SLI showed impairments in repeating low-lexicality nonwords but were unimpaired with high-lexicality nonwords.
• Repetition accuracy for low-lexicality nonwords improved with higher phonotactic frequency of phoneme sequences.
• Error patterns in children with SLI were similar to TD children, suggesting lexical substitution rather than pure phonological errors.

Conclusions:

• The findings support a phonological processing deficit in SLI, mediated by lexical and sublexical knowledge.
• Nonword interpretation relies on existing long-term phonological knowledge.
• While phonological processing is key, a comprehensive explanation of SLI likely involves multiple factors.