The role of mediators in memory retrieval as a function of practice: controlled mediation to direct access.

The role of prior knowledge in retrieval of Spanish-Engli sh vocabulary pairs learned using keyword mediators was examined in 4 experiments. Retrieval was tested immediately after learning and after 1-week and 1-month no-practice intervals (Experiment 1), after moderate retrieval practice (Experiment 2), and after extended retrieval practice (Experiments 3 and 4). Using accuracy, latency, and verbal report data, a detailed account of memory retrieval processes was developed. Initial retrieval is an explicit mediation process that involves retrieving keyword mediators into working memory and using them as retrieval cues to access the English equivalents of the Spanish words. After extended vocabulary retrieval practice, this sequential mediation process qualitatively changed to a direct retrieval process in which the English equivalent was accessed in a single working memory step. However, direct retrieval was still influenced by a covert mediation process. An important issue in cognitive research is the role of prior knowledge and experience in cognitive processes. Evidence from a number of different research domains, including the study of expertise (Chase & Simon, 1973; Ericsson & Lehmann, 1996), exceptional memory (Chase & Ericsson, 1982; Ericsson & Kintsch, 1995; Wilding & Valentine, 1997), and mnemonics (Bellezza, 1981; Ericsson, 1985; Pressley, Levin, & Delaney, 1982), suggests that differences in prior knowledge and experience are associated with rather large differences in memory performance. However, the specific role of prior knowledge in mediating improved learning and memory processes is still not well understood. An important question, and the concern of the research reported here, involves determining the role played by the knowledge used initially to encode new material in subsequent memory retrieval processes and how that role changes as a function of repeated access of the memory system. We briefly review previous