Why are children with early speech sound disorders at risk for literacy difficulties?
There are many possible explanations. Perhaps these children have “fuzzy” phonological representations. They sometimes have poor phonological awareness skills, poor verbal short-term memory, reduced vocabulary, and slow lexical retrieval. They can also have a series of co-morbid conditions such as attentional problems, co-morbid language impairment. They can have poor orthographic awareness and reduced narrative abilities. All of these co-morbid conditions contribute to literacy skills.
There have been two proposed explanations for the relationship of speech sound disorders to reading. One, as previously stated, is that phonological representations may be degraded, “fuzzy,” and underspecified resulting in the loss of some phonetic features before they can be compared or repeated. Therefore, the student has poor decoding skills. Another possibility is that phonological representations are intact and phonetic features are correctly encoded, but short-term memory processes are limited. The student has difficulty transferring information into working memory, which then disrupts reading comprehension.
It is important to emphasize that not all children with SSD have reading difficulties. One study reported that 22% of 7 to 9 year old children with SSD have reading difficulties. Twenty-two percent is still a large number, but it is not every child with SSD. We also know that children with SSD may have phonological deficiencies, but no reading difficulties. Children with SSD have been shown to score more poorly on phonological awareness skills and single word reading than their typical peers. Some researchers have suggested that it is the children who have non-developmental phonological process errors that are more likely to have decoding difficulties.