Separating input and output phonology: Semantic, phonological, and orthographic effects in short-term memory impairment

Recent research with both normal and brain-damaged people shows that linguistic representations are important sources of information in short-term memory tasks. This paper addresses the role of semantic and phonological information in the performance of two individuals with severely impaired short-term memory span (HB and MMG). The performance of these individuals is investigated on span tasks manipulating, for example, lexicality, imageability, word length, and phonological similarity, as well as on their ability to perform other tasks involving the judgment and/or manipulation of phonology (e.g., rhyme judgments, phonological lexical decision, segmentation tasks, and minimal pairs). The subjects' performance across these tasks provides strong evidence for separate but linked language and short-term memory systems, with lexical and semantic representations contributing to immediate serial recall. There is also evidence for separate phonological and semantic short-term stores (buffers), each of which are supported by the corresponding representations in the language system. Furthermore, the results support separate phonological stores at input and output. Finally a cautionary note is cast regarding the significant role of orthography in many tasks previously assumed to reflect manipulation of phonology.