Preserved Learning and Retention of Pattern-Analyzing Skill in Amnesia: Dissociation of Knowing How and Knowing That

Abstract

Amnesic patients acquired a mirror-reading skill at a rate equivalent to that of matched control subjects and retained it for at least 3 months. The results indicate that the class of preserved learning skills in amnesia is broader than previously reported. Amnesia seems to spare information that is based on rules or procedures, as contrasted with information that is data-based or declarative--"knowing how rather than "knowing that." The results support the hypothesis that such a distinction is honored by the nervous system.

The hippocampal debate: are we asking the right questions?

“…Most memory researchers accept the hypothesis that there are multiple memory systems in the brain [33,35,120,140,211]. Similarly, most navigation researchers accept the hypothesis that there are multiple navigation systems in the brain [150,173].…”

“…When H.M. recovered from his surgery, his doctors discovered a profound anterograde and retrograde amnesia [198]. Further tests noted that only some aspects of memory were impaired, particularly those generally described as declarati6e (such as remembering incidents, numbers, or lists of unrelated words [35,116,198]); other abilities were still intact, particularly those generally described as procedural (such as mirror-reading [35], mirror-writing [116], and rotarypursuit [36]). …”

New Look 3: Unconscious cognition reclaimed.

“…On being pressed, the patient stated, "Sometimes pins are hidden in people's hands," but did not understand this to be a memory (p. 70). In the past 20 years or so, similar observations have been gathered much more systematically as researchers developed tasks that revealed amnesics' performance gains from unrecallable practice trials (e.g., Cohen & Squire, 1980;Warrington & Weiskrantz, 1968). Present understanding of the theoretical significance of amnesics' mnemonic abilities has been greatly expanded by the work of Jacoby (who provides an overview in this issue-Jacoby et al, 1992).…”

Implicit/explicit memory dissociation in Alzheimer's disease: The consequence of inappropriate processing?

“…In light of this background, the mere exposure effect falls into the same broad implicit memory category as perceptual priming, that is, the facilitation of or bias in the processing of a stimulus as a function of a recent encounter with that stimulus (Butler & Berry, 2004;Seamon et al, 1995). To explain this kind of implicit-explicit dissociation, some authors have proposed that perceptual priming may be mediated by a memory system (e.g., perceptual representation system or procedural memory system) separate from the system that mediates explicit memory (e.g., episodic or declarative memory system) (Cohen & Squire, 1980;Graf & Schacter, 1985;Seamon et al, 1995;Squire, 1992;Tulving & Schacter, 1990). Along these lines, it has been shown that in AD the extrastriatal cortex -where reduced activation is often associated with perceptual priming in the visual modality -remains considerably less prone to neurofibrillary tangle formation than the multimodal association and limbic cortices, which are known to be critical to the memory system that mediates explicit memory performance (Arnold, Hyman, Flory, Damasio, & Van Hoesen, 1991;Pietrini et al, 1999).…”