Working memory deficits in poor comprehenders reflect underlying language impairments

Three experiments assessed memory skills in good and poor comprehenders, matched for decoding skill. Experiments 1 and 2 investigated phonological and semantic contributions to short-term memory by comparing serial recall for words varying in length, lexicality, and concreteness. Poor comprehenders showed normal sensitivity to phonological manipulations (length and lexicality) but, consistent with their semantic weaknesses, their recall of abstract words was poor. Experiment 3 investigated verbal and spatial working memory. While poor comprehenders achieved normal spatial spans, their verbal spans were impaired. These results are discussed within a theoretical framework in which the memory difficulties associated with poor reading comprehension are specific to the verbal domain and are a concomitant of language impairment, rather than a cause of reading comprehension failure.