Conscious and unconscious processes in hypermnesia

Hajime Otani, Koichi Kato, Robert L. Widner

Research output: Chapter in Book/Report/Conference proceedingChapterpeer-review

2 Scopus citations


Memory performance changes as a function of repeated testing even when we are not re-exposed to the to-be-remembered material between tests. Our research has focused on whether recovery of previously unretrieved items on a subsequent test-referred to as reminiscence-is based on conscious or unconscious processes. There is ample evidence indicating that reminiscence requires active searches of memory (i.e., conscious process). However, subjective experiences suggest that previously unretrieved items sometime pop into mind without an active search of memory (i.e., unconscious process). In line with this hypothesis, studies have shown that (1) tip-of-the-tongue experiences are often resolved when the sought-after information pops into mind; (2) participants often have no knowledge of items prior to recovering these items; and (3) unlike recall, older adults show similar levels of reminiscence as do young adults. However, when one compares data from explicit and implicit memory tests, the explicit test produces greater amounts of reminiscence than the implicit test, even though reminiscence is also present in the implicit memory test. Based on these results, we suggest that there are two types of reminiscence, voluntary and involuntary; the former requires conscious retrieval whereas the latter does not. The existence of these two types of reminiscence suggests that when retrieval attempts for sought-after information are repeated, memory performance is determined by the dynamic interplay between conscious and unconscious processes.

Original languageEnglish
Title of host publicationDynamic Cognitive Processes
PublisherSpringer Tokyo
Number of pages23
ISBN (Print)4431239995, 9784431239994
StatePublished - 2005


  • Repeated testing
  • automatic processing
  • hypermnesia
  • reminiscence
  • voluntary and involuntary reminiscence


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