Phonological decoding skill has been proposed to be key to successful sight word learning (orthographic learning). However, little is known about how children with phonological dyslexia, who have impaired phonological decoding, acquire sight words, or why children with surface dyslexia can have normal phonological decoding skill yet impaired sight word acquisition. This study addressed this issue by investigating orthographic learning in two 10-year-old children: S.D., with a reading profile of surface dyslexia, and P.D., with a reading profile of phonological dyslexia. They participated in two experiments exploring the role of phonological decoding and paired-associate learning in orthographic learning. The results showed that, first, P.D.'s orthographic learning ability was better than S.D.'s, despite her phonological decoding skills being poorer. Second, S.D. showed impaired paired-associate learning abilities while P.D. did not. Overall, the results indicate that phonological decoding ability does not translate directly to orthographic learning ability, and that paired-associate learning ability may also be associated with success in orthographic learning.
Keywords: developmental dyslexia; orthographic learning; paired-associate learning; subtypes of dyslexia.