Wednesday, January 25, 2017

Working Memory in Children with Learning Disabilities in Reading Versus Spelling: Searching for Overlapping and Specific Cognitive Factors

The written language (orthography) of English is considered opaque because the letters in a word don’t always correspond to the sounds of that word when spoken. Of course, the word ‘AND’ is transparent: It has three letters, each of which correspond as expected to the common sounds those letters make. But, the word ‘WERE’ is opaque: The letters don’t correspond all that well to the sounds in the spoken word. There are lots of these ‘irregular words’ in English writing, so English orthography is considered opaque. Importantly, opaque orthographies are difficult to read because the words on the page don’t always predict the sounds in the word, AND spell because the sounds you want to write might correspond to different possible letter patterns. As would be expected, then, many studies demonstrate that English children who have difficulty reading, also have difficulty spelling.

German orthography, on the other hand, is considered transparent because the letters in the written words correspond well to the sounds of that word when spoken. That makes reading easier: You can sound out the corresponding sounds in the written word to decode the word. Nevertheless, there can be different ways to spell a sound in German (e.g., /ee/ can be spelled ‘ee’ or ‘eh’). As a result, spelling requires more processing of the individual sounds in a word, or more phonological processing.  Branderburg et al. reasoned that reading and spelling problems may not always co-occur in German children, and that different impairments might be associated with different cognitive processes.

The researchers compared the performance of 3rd grade children with either reading disorder, spelling disorder, reading and spelling disorder, or no reading and spelling disorder (control group) on measures tapping phonological processing (short-term memory; speaking rate) or working memory (the ability to store and process phonological information). The results revealed phonological short-term memory impairments in children with spelling disorder compared to the control group, and working memory impairments in children with reading disorder compared to the control group.

The results provide further support for the important role of phonological processing in supporting literacy, especially when there is some ambiguity in the correspondence between letters and sounds. The findings also highlight the cognitive demands of reading possibly related to supporting reading comprehension processes.

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