Lexical coherence in short-term memory: strategic reconstruction or "semantic glue"?

This study explores the foundation of lexical/semantic phoneme binding effects in verbal short-term memory (STM). The immediate serial recall of pure lists of words and nonwords was compared with the recall of mixed lists that had either a predictable, alternating structure (e.g., wnwnwn) or an unpredictable structure (i.e., the serial positions of the words/nonwords could not be known in advance). The study provides evidence for two separate mechanisms by which long-term linguistic knowledge contributes to STM. First, there was evidence for automatic lexical/semantic binding effects that were independent of knowledge of lexical status. The nonwords in both types of mixed list damaged word recall and encouraged the phonological elements of words to migrate. In both alternating and unpredictable mixed lists, the phonemes of words were more likely than the phonemes of nonwords to be recalled together as a coherent item, suggesting that lexical/semantic knowledge encourages the phonological elements of words to emerge together in immediate serial recall, even when lexical status is unknown. Secondly, there was evidence for "strategic redintegration", which was dependent on prior knowledge of the lexical status of the items in mixed lists. When participants recalled items that they knew to be words in advance, they were able to use this knowledge to constrain their responses so that they were more likely to be lexically appropriate. These findings motivate modifications to current theories of the interaction between linguistic knowledge and verbal short-term memory.