Verbal short-term memory in individuals with congenital articulatory disorders: new empirical data and review of the literature

Abstract

Background: To investigate the nature of the articulatory rehearsal mechanism of the Articulatory Loop in Baddeley's Working Memory model, it seems particularly important to study individuals who developed a deficit (dysarthria) or total abolition (anarthria) of the ability to articulate language following a cerebral lesion.

Method: In this study, a forced-choice recognition procedure for word sequences of increasing length was used to evaluate verbal short-term memory in nine individuals with severe congenital motor and verbal disabilities (seven anarthric and two severely dysarthric) and associated intellectual disability (ID) and 30 normal children of comparable mental age.

Results: The normal children exhibited classical phonological similarity effects (better performance on acoustically dissimilar than on similar word lists), word length (greater accuracy on two-syllable than on four-syllable word lists) and frequency of occurrence (an advantage of high-frequency over low-frequency words). Instead, all of these effects were lacking in the experimental group.

Conclusions: These data suggest that persons with congenital anarthria/dysarthria and ID present defective maturation at many levels of the Articulatory Loop and reduced contribution of semantic-lexical processing in the temporary retention of phonological sequences. It is likely that in these individuals both communicative deficits and ID play a role in the impaired development of verbal short-term memory abilities.