Dissociative contributions of semantic and lexical-phonological information to immediate recognition.

Several neuropsychological studies have reported that patients with memory deficits exhibit a dissociation of effects attributed to semantic and lexical-phonological information in verbal working memory (e.g., Reilly, Martin, & Grossman, 2005; Romani & Martin, 1999). The present study reports on 3 experiments conducted with individuals without memory problems to examine the dissociation between the word imageability effect (WIE) and the word frequency effect (WFE). Experiment 1 used a modified semantic recognition task, in which participants were presented with 10-item lists and selected synonyms of list words from among 5 words. This task led to a significant WIE but no WFE. On the other hand, Experiment 2 used a modified recognition task in which targets were homophones, to promote the usage of phonological information while minimizing the potential impact of semantic information. There was no WIE but a significant WFE in Experiment 2. Experiment 3 replicated the results of Experiment 1 using 5-item lists and a 2-alternative forced choice procedure. Taken together, these results systematically replicate the double dissociation observed in neuropsychological studies. These findings suggest that semantic information can contribute to successful retrieval from verbal working memory without mediation from lexical-phonological information.