Restoring primacy in amnesic free recall: Evidence for the recency theory of primacy

Abstract

Primacy and recency effects at immediate recall are thought to reflect the independent functioning of a long-term memory store (primacy) and a short-term memory store (recency). Key evidence for this theory comes from amnesic patients who show severe long-term memory storage deficits, coupled with profoundly attenuated primacy. Here we challenge this dominant dual-store theory of immediate recall by demonstrating that attenuated primacy in amnesic patients can reflect abnormal working memory rehearsal processes. D.A., a patient with severe amnesia, presented with profoundly attenuated primacy when using her preferred atypical noncumulative rehearsal strategy. In contrast, despite her severe amnesia, she showed normal primacy when her rehearsal was matched with that of controls via an externalized cumulative rehearsal schedule. Our data are in keeping with the “recency theory of primacy” and suggest that primacy at immediate recall is dependent upon medial temporal lobe involvement in cumulative rehearsal rather than long-term memory storage.

Keywords:

• Amnesia
• Primacy effect
• Free recall
• Short-term memory
• Rehearsal

Acknowledgments

This research was supported by postdoctoral research fellowships to M. Dewar from Alzheimer's Research UK and the Royal Society of Edinburgh/Lloyds TSB Foundation for Scotland, and by an Economic and Social Research Council (UK) grant to G. Brown (RES-062-23-2462). We thank D.A. and all controls who volunteered to take part in this study and Beata Michalska who helped with the collection of control data. We are grateful to the editor and three anonymous reviewers for their very helpful comments on this manuscript. All clinical data listed in Table 1 (apart from the Rivermead Behavioural Memory Test) were collected by Sharon Abrahams during formal clinical neuropsychology assessment.