Phonological encoding in speech-sound disorder: evidence from a cross-modal priming experiment

Background: Psycholinguistic models of language production provide a framework for determining the locus of language breakdown that leads to speech-sound disorder (SSD) in children. Aims: To examine whether children with SSD differ from their age-matched peers with typical speech and language development (TD) in the ability phonologically to encode lexical items that have been accessed from memory. Methods& Procedures: Thirty-six children (18 with TD, 18 with SSD) viewed pictures while listening to interfering words (IW) or a non-linguistic auditory stimulus presented over headphones either 150 ms before, concurrent with or 150 ms after picture presentation. The phonological similarity of the IW and the pictures' names varied. Picture-naming latency, accuracy and duration were tallied. Outcomes & Results: All children named pictures more quickly in the presence of an IW identical to the picture's name than in the other conditions. At the + 150 ms stimulus onset asynchrony, pictures were named more quickly when the IW shared phonemes with the picture's name than when they were phonologically unrelated to the picture's name. The size of this effect was similar for children with SSD and children with TD. Variation in the magnitude of inhibition and facilitation on cross-modal priming tasks across children was more strongly affected by the size of the expressive and receptive lexicons than by speech-production accuracy. Conclusions & Implications: Results suggest that SSD is not associated with reduced phonological encoding ability, at least as it is reflected by cross-modal naming tasks.