Source accuracy data reveal the thresholded nature of human episodic memory

Iain M. Harlow, David I. Donaldson

Research output: Contribution to journalArticlepeer-review

49 Citations (Scopus)


Episodic recollection supports conscious retrieval of past events. It is unknown why recollected memories are often vivid, but at other times we struggle to remember. Such experiences might reflect a recollection threshold: Either the threshold is exceeded and information is retrieved, or recollection fails completely. Alternatively, retrieval failure could reflect weak memory: Recollection could behave as a continuous signal, always yielding some variable degree of information. Here we reconcile these views, using a novel source memory task that measures retrieval accuracy directly. We show that recollection is thresholded, such that retrieval sometimes simply fails. Our technique clarifies a fundamental property of memory and allows responses to be accurately measured, without recourse to subjective introspection. These findings raise new questions about how successful retrieval is determined and why it declines with age and disease.

Original languageEnglish
Pages (from-to)318-325
Number of pages8
JournalPsychonomic Bulletin and Review
Issue number2
Publication statusPublished - 12 Mar 2013


  • Episodic memory
  • Familiarity
  • Human memory
  • Recollection
  • Signal detection theory


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