Phonological similarity effects, memory span and developmental reading disorders: the nature of the relationship.

Eight-and 11-year-old poor readers of average and below average intelligence carried out a visually presented immediate memory task, recalling strings of similar- and dissimilar-sounding letters. Task difficulty was adjusted for each child by determining memory span for the dissimilar items prior to the memory task. All poor reader groups recalled significantly more dissimilar- than similar-sounding items, and the magnitude of these effects was comparable to those shown by their chronological and reading age controls. A close association was found between memory span and reading age, such that average intelligence poor readers had memory spans indistinguishable from those of their reading age controls. Furthermore, a highly significant correlation was found between memory span and reading age. However, it was concluded that this relationship could not be primarily due to a substantial immediate memory component in word recognition as the below average intelligence poor readers had poorer memory spans than the brighter poor readers, yet they had very similar reading ages. Additionally, a weaker association was found between memory span and non-word reading than between memory span and word reading. It was hypothesized that recognition difficulties may be the primary problem underlying both poor word recognition and immediate memory impairments in children with reading disorders.