Spelling abilities of school-aged children with Williams syndrome

We examined the relation between spelling ability and word-reading ability in children with Williams syndrome (WS).

Eighty 9-17-year-olds with genetically-confirmed WS completed standardized tests of spelling, word reading, and intellectual ability; 45 also completed tests of phonological awareness and vocabulary. Reading instruction method was classified as Phonics or Other.

Spelling ability varied widely. Although at the group level, spelling standard scores (SSs) were significantly lower than word-reading SSs, at the individual level, this difference was significant for fewer than half the participants. Spelling and reading SSs were highly correlated, even after controlling for intellectual ability. Students taught to read using systematic phonics instruction had significantly higher spelling SSs than those taught to read using other approaches, even after controlling for intellectual ability. Spelling ability contributed significant unique variance to word-reading ability, beyond the effects of phonological awareness, vocabulary, and reading instruction method.

Our findings are consistent with Ehri's Word Identity Amalgamation Theory. In combination with previous meta-analytic findings for typically developing children (Graham & Santangelo, 2014) our results suggest that children with WS are likely to benefit from the inclusion of systematic spelling instruction as part of a systematic phonics approach to teaching word reading.