Psychology, Department of


Date of this Version



Published in Published in Journal of Experimental Psychology: Applied 14:2 (2008), pp. 139-150; doi 10.1037/1076-898X.14.2.139 Copyright © 2008 American Psychological Association. Used by permission. “This article may not exactly replicate the final version published in the APA journal. It is not the copy of record.”


The fidelity of an eyewitness’s memory representation is an issue of paramount forensic concern. Psychological science has been un¬able 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. Wick¬elgren’s (1974, 1975, 1977) theory of recognition memory provided statistically satisfactory fits to 11 different empirical forgetting func¬tions. 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.