Evaluating Phonological Short-Term Memory in Children with SLI: A Comparative Analysis of Serial Order, Item...

Nonword repetition (NWR) and related verbal short-term memory (STM) tasks are widely used to characterise cognitive deficits in children with Specific Language Impairment (SLI). However, growing evidence suggests that performance on these tasks reflects not only memory processes but also the contribution of linguistic representations, raising questions about their interpretation as measures of phonological STM. The present study examined STM performance in Cantonese-speaking children with SLI (n = 18) and age-matched typically developing peers (n = 18) using three tasks: nonword repetition, serial order reconstruction, and delayed item repetition. Crucially, the study incorporated systematic manipulations of linguistic characteristics, including pseudo-morpheme versus pseudo-syllable stimuli in NWR and word versus nonword stimuli in delayed item repetition, to evaluate the influence of lexical and sublexical structure on task performance. Results showed that children with SLI performed significantly worse than peers across all tasks. However, performance was strongly modulated by linguistic factors. Both groups exhibited lexicality effects, with higher accuracy for pseudo-morphemes than pseudo-syllables in NWR and for words than nonwords in delayed item repetition. Group differences were most pronounced in conditions with greater lexical support, whereas performance converged when linguistic support was minimal. These findings indicate that verbal STM performance in SLI is best understood in terms of reduced efficiency in the interaction between STM processes and phonological representations, rather than a unitary memory deficit. The study highlights the importance of considering linguistic characteristics when interpreting STM tasks and demonstrates the value of using controlled manipulations to disentangle memory and language contributions in SLI.