Implicit and explicit tests: evidence for dissociable motor skills in probable Alzheimer's dementia

Previous authors reported evidence for intact implicit memories (those retrieved without conscious effort) in a serial reaction time task for both Alzheimer's subjects and age-matched controls, although performance on an explicit memory task (requiring conscious effort for retrieval) was poor. The current study assessed latencies on a puzzle-assembly task to assess implicit (procedural) memory for 23 female volunteers. Nine participants suffered from probable Alzheimer's Disease and fourteen did not. Even when subjects had no explicit memory of practicing the task, they demonstrated savings upon relearning. Implications for research on memory dissociations in Alzheimer's Disease are discussed.