Sporer, S. L., Penrod, S., Read, D., & Cutler, B. (1995). Choosing, confidence, and accuracy: A meta-analysis of the confidence-accuracy relation in eyewitness identification studies. Psychological Bulletin, 118, 315-327.
Sporer et al., (1995) present an in depth meta-analysis conducted using results and data from previous studies examining the relation between confidence-accuracy. Thirty studies were used in the meta-analysis which used some kind of mock crime event in their methodology, used both target present and target absent lineups, had collected both confidence and accuracy measures from participants, and still had raw data to use for further analyses. The main addition to the existing research on the CA relation in the meta-analysis is the examination of the moderator variable of whether or not people identify someone out of a lineup or do not make an identification.
Clearly the processes would be different for those who choose compared to those who do not choose someone from a lineup. The authors cite evidence from Bem's (1972) self-perception theory regarding the notion that the act of making some kind of decision, rather than indecisiveness, should result in greater confidence in the ability to have made a worthwhile decision (i.e., in the case of eyewitness identification, an accurate one). Thus, stemming from the notion of these inherent differences between choosers and non-choosers, Sporer et al., (1995) ran separate analyses for choosers (those who chose either a correct or incorrect person from the lineup) versus non-choosers (those who rejected the lineup). The effect sizes for choosers were much higher than for non-choosers, even for weighted effect size estimates. The real interesting thing is that the effect sizes, weighted, were higher than the overall effect size with both choosers and non-choosers included. Additionally, those who chose were much more confident compared to those who did not make an identification from the lineup. This indicates the strong role of the moderator variable of being a chooser or a non-chooser when faced with making a lineup identification decision.
Being a meta-analysis, the article provides a variety of information from the various studies examined, including whether or not the mock crime event was live or recorded to video, gender of the target, scale range used for confidence statements, proportion of correct identifications, and correct decisions broken down for choosers and non-choosers. This is an excellent review of the CA relation by some of the biggest and well known researchers in the field of eyewitness identification. If you only had time to read one article about the relation between eyewitness confidence and accuracy, I would recommend you read Sporer et al., (1995).
--By DJP
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