Forgetting the Once-Seen Face: Estimating the Strength of an Eyewitness's Memory Representation

Kenneth A. Deffenbacher, Brian H. Bornstein, E. Kiernan McGorty, Steven D. Penrod

Research output: Contribution to journalArticlepeer-review

88 Scopus citations


The fidelity of an eyewitness's memory representation is an issue of paramount forensic concern. Psychological science has been unable to offer more than vague generalities concerning the relation of retention interval to memory trace strength for the once-seen face. A meta-analysis of 53 facial memory studies produced a highly reliable association (r = .18, d = 0.37) between longer retention intervals and positive forgetting of once-seen faces, an effect equally strong for both face recognition and eyewitness identification studies. W. A. Wickelgren's (1974, 1975, 1977) theory of recognition memory provided statistically satisfactory fits to 11 different empirical forgetting functions. Applied to the results of field studies of eyewitness memory, the theory yields predictions relevant to fact finders' evaluations of eyewitness credibility. A plausible upper limit for witness initial memory strength corresponds to a probability of .67 of being correct on a fair six-person lineup. Furthermore, not only can the percentage of remaining memory strength be determined for any retention interval, but this strength estimate can be translated into an estimated probability of being correct on a fair lineup of a specified size.

Original languageEnglish (US)
Pages (from-to)139-150
Number of pages12
JournalJournal of Experimental Psychology: Applied
Issue number2
StatePublished - Jun 2008
Externally publishedYes


  • eyewitness memory strength
  • forgetting of faces
  • retention interval
  • single-trace fragility theory

ASJC Scopus subject areas

  • Experimental and Cognitive Psychology


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