Implicit expressions of memory in organic amnesia: learning of new facts and associations.

Organic amnesia is a selective impairment of memory that occurs as a consequence of various types of brain damage. Although amnesic patients typically have severe difficulties remembering recent events and acquiring new information, it has been demonstrated that some of their learning abilities are spared. Amnesic patients can retain and express some aspects of a learning experience, despite their inability to recollect the experience in a conscious or explicit manner. This phenomenon is referred to as an implicit expression of memory. The present article considers whether amnesic patients show implicit memory for new facts and associations. Three relevant kinds of evidence are considered: source amnesia, priming effects, and learning of computer vocabulary and commands. It is concluded that (a) amnesic patients do show some implicit memory for new facts and associations, and (b) this type of memory is not entirely spared. Implications for multiple memory system views of amnesia are discussed.