Recently in Confidence Accuracy Category

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 

 

 

Luus, C. A. E., & Wells, G. L. (1994). The malleability of eyewitness confidence: Co-witness and perseverance effects. Journal of Applied Psychology, 79, 714-723.

            Luus and Wells (1994) provide an excellent study regarding the extent to which confidence of eyewitnesses can change and vary based on information they receive from various sources, especially regarding information about others decision making processes for lineups. Their study incorporates a very social psychological design with a traditional eyewitness identification approach in which participants are shown a crime video, asked to identify the person they saw commit the crime from a lineup, and then indicate how confident they are in their decision. The twist with this study is they then told participants, assigned to various conditions, information about other people's decisions on the lineup (i.e., same, different, etc.). Thus, participants receiving information indicating that another person picked the same face out of a lineup that they did, exhibited an increase in confidence. Those hearing from the confederates of the experiment regarding people who disagreed with their decision or rejected the lineup, indicated much lower confidence statements relative to other conditions of the experiment in which agreement occurred.

            In their next experiment, the researchers showed the videotaped lineup administrations complete with the decision, confidence, and induction of false information recorded from Experiment 1, to a new sample of participants to rate how accurate they perceived the participants in the various conditions in Experiment 1 to be regarding the decision made. They found that when viewing a recording of the inflated confidence conditions, participants predicted higher accuracy to result based on their confidence statements, compared to recordings of the confidence deflated conditions.

            This study provides a nice review of the malleability of confidence judgments and also tells a cautionary tale of how law enforcement officials and others who may influence eyewitness confidence with information or positive feedback regarding decisions made, should consider the potential harmful impact of the information they provide to witnesses.

--By DJP

Deffenbacher, K. A. (1980). Accuracy and confidence: Can we infer anything about their relationship? Law and Human Behavior, 4, 243-260.

            Deffenbacher (1980) provides a review of many of the earlier studies conducted on the relationship between eyewitness confidence and accuracy. As can be seen, the relationship between confidence and accuracy is not a reliable one and a variety of methods have been used to conduct research ranging from finding either significant positive correlations or no correlation at all. In addition to providing somewhat of a review of research literature examining this important topic, Deffenbacher provides a theory regarding the disparity in results regarding findings of various correlations between confidence and accuracy with reliability coefficients of an unimpressive magnitude. He proposes an optimal processing hypothesis attempting to explain why certain studies find high positive correlations between confidence and accuracy and why others find near zero or negative correlations.


            Under optimal conditions, the relationship between confidence and accuracy is thought to be high, yet under less than optimal conditions the relationship will decrease to chance levels or produce evidence of a negative relationship between the two variables. There is evidence to support the optimality hypothesis, with results indicating significant positive correlations based on methodologies in which the procedural phases of the experiment (i.e., encoding, retrieval) were carried out under conditions sufficient for optimal processing of information. Additionally, studies in which participants encoded and attempted to retrieve information regarding an event were conducted within low or poor processing conditions (i.e., noise, outdoors, low luminance) no significant positive correlations, and in some instances negative correlations, were found.

On the other hand, certain studies have found results which run counter to the proposals stemming from the optimality hypothesis. For example, certain studies using procedures conducive to optimal processing of information have found non-significant or negative correlations for the confidence and accuracy relationship. Thus, we researchers and those in the area of law enforcement need to be especially careful regarding attempts to predict accuracy from eyewitness confidence statements. Jurors may also be affected, because they are likely to be influenced by confidence statements (especially when high) made by witnesses, and infer accuracy from them (Wells, Lindsay, & Ferguson, 1979).  It is important that all those using or examining confidence statements made by witnesses are extremely careful when interpreting or estimating how well they provide information relate to accuracy of a identification.

--By DJP