The Effect of Retention Interval on the Confidence–Accuracy Relationship for Eyewitness Identification James Sauer Æ Neil Brewer Æ Tick Zweck Æ Nathan Weber
Published online: 22 July 2009
Ó American Psychology-Law Society/Division 41 of the American Psychological Association 2009 Abstract Recent research using a calibration approach indicates that eyewitness confidence assessments obtained immediately after a positive identification decision provide a useful guide as to the likely accuracy of the identification. This study extended research on the boundary conditions of the confidence–accuracy (CA) relationship by varying the retention interval between encoding and identification test. Participants (N = 1,063) viewed one of five different tar- gets in a community setting and attempted an identification from an 8-person target-present or -absent lineup either immediately or several weeks later. Compared to the immediate condition, the delay condition produced greater overconfidence and lower diagnosticity. However, for choosers at both retention intervals there was a meaningful CA relationship and diagnosticity was much stronger at high than low confidence levels. Keywords Eyewitness identification Confidence–accuracy Retention interval Calibration Criminal justice systems often use eyewitness identifica- tion evidence when assessing the likely guilt of a suspect or defendant. Yet, the likelihood of eyewitness identification error is well documented by laboratory- and field-based research demonstrating that, when presented with a lineup J. Sauer N. Brewer (&) T. Zweck N. Weber
School of Psychology, Flinders University, GPO Box 2100, Adelaide, SA 5001, Australia e-mail: firstname.lastname@example.org
Department of Psychology, University of Portsmouth, Portsmouth, UK and asked to make an identification decision, witnesses sometimes (a) misidentify innocent lineup members as the culprit or (b) fail to identify the culprit when (s)he is present in the lineup (Cutler & Penrod, 1995; Innocence Project, 2009; Pike, Brace, & Kynan, 2002; Wells et al., 1998). Such identification errors divert investigative attention from the actual culprit and are likely to under- mine the effectiveness of the criminal justice system. Their impact has motivated a substantial amount of research aimed at identifying markers capable of discriminating accurate from inaccurate identification decisions. Eyewitness confidence is one possible marker of iden- tification accuracy that has been used by forensic decision makers. Not only has confidence been endorsed by the U.S. Supreme Court as one of the criteria to be considered when assessing the likely accuracy of identification evidence (Neil v. Biggers, 1972) but there is also a substantial literature demonstrating that eyewitness confidence influences assessments of likely identification accuracy made by police officers, lawyers, jurors, and jury-eligible samples (e.g., Bradfield & Wells, 2000; Brewer & Burke, 2002; Cutler, Penrod, & Stuve, 1988; Deffenbacher & Loftus, 1982; Lindsay, Wells, & Rumpel, 1981). Moreover, there are sound theoretical grounds for pre- dicting a meaningful confidence–accuracy (CA) relationship for eyewitness identification decisions, which are a form of recognition memory decision. A number of theories of decision making and confidence processing—such as signal detection theory (Egan, 1958; Green & Swets, 1966; Mac- millan & Creelman, 1991) and accumulator models of decision making and perceptual discrimination (Van Zandt, 2000; Vickers, 1979)—suggest a shared evidential basis for response and response confidence in recognition memory tasks. Both classes of theory hold that confidence stems from the same evidence that drives the decision-making ￼123
Law Hum Behav (2010) 34:337–347
￼process and, consequently, conditions facilitating accurate responding (e.g.,...