A comparison of implicit memory tasks in Korsakoff and alcoholic patients.

Korsakoff patients generally perform at a normal level on implicit memory tasks in contrast to explicit memory tasks. While this difference is sometimes explained in terms of different memory systems underlying the tasks, the different roles of perceptual and conceptual/semantic processes in these tasks have also been emphasized: explicit tasks require mainly conceptual/ semantic processes and implicit tasks are based principally on perceptual processes. However, it has been suggested recently that conceptual/semantic processes may also be involved in some implicit memory tasks (e.g. a Free Association task). Therefore, the performance of Korsakoff and alcoholic patients is here compared in three implicit memory tasks (Stem Completion, Word Identification and Free Association) and one explicit memory task (Cued Recall), allowing us to disentangle what really matters: the nature of the task (implicit or explicit), or the underlying processes (perceptual or conceptual/semantic). The results show only semantic priming in the Free Association and Cued Recall tasks of the alcoholic patients, suggesting that Korsakoff patients have problems particularly with conceptually-driven processing. The implicit or explicit nature of the memory task is not critical.