A comparison of orthographic processing in children with and without reading and spelling disorder in a regular orthography

Orthographic processing is a construct that encompasses the skills of recognizing, storing, accessing, and applying the print conventions of a writing system. Few studies have investigated orthographic processing in dyslexic children and it is not yet clear whether lexical and sublexical orthographic processing are both impaired in these children. The present study examined orthographic processing in dyslexic children (N = 19, below-average word reading as well as below average spelling skills, T-values < 40) and typically developing children (N = 32) aged 8-10 years. Different aspects of orthographic processing were measured. Word-specific knowledge (lexical level) was assessed with an Orthographic Choice Task. General orthographic knowledge (sublexical level) was assessed with three pseudoword tasks. The Freq-Choice-Task is a choice task that measures children's knowledge of frequent double consonants (e.g., nilemm-nilebb). The Pos-Choice-Task measures children's knowledge about legal positions of double consonants (e.g., sinnum-ssinum). The Pos-Speed-Task measures children's ability to identify orthographic irregularities in words presented singly (e.g., mmotin). Results show that dyslexic children are able to discriminate illegal/infrequent letter pattern from legal/frequent letter pattern. Seeing either a word with legal or illegal letter patterns singly (Pos-Speed-Task), dyslexic children show deficits in identifying illegal letter pattern as wrong, whereas they have no problems to identify legal letter pattern as correct. Furthermore, dyslexic children show a reduced word specific orthographic knowledge. Additionally, the present study demonstrated that word representations as well as sensitivity to legal letter pattern influence reading and spelling performance.