Morphological patterns in Hungarian children with Williams syndrome and the rule debates.

Williams syndrome (WMS), a rare neurogenetic disorder, has been in the forefront of research in cognitive psychology for the last 10 years. Studies of grammatical development in 14 Hungarian WMS children are presented: they were examined on tasks testing regular and irregular morphology; measures of digit span were also obtained. Results on the production of accusative and plural forms confirmed for Hungarian that regardless of the frequency of the item, inflected forms of irregulars are harder to produce, and often regularized in WMS, revealing a dissociation between the rules of grammar vs. the mental lexicon. Overall performance on the morphology task is associated with the capacity of phonological short-term memory: subjects with higher span perform better on both tasks. The specification of the surprisingly close relation of phonological short-term memory with the linguistic measures awaits further study.