Context Influences Interpretation of Eyewitness Confidence Statements

When an eyewitness makes an identification from a lineup, he or she is asked to provide a confidence statement to help jurors assess credibility. However, these are verbal statements and people must rely on metacognitive processes to correctly interpret them. Recently, Dodson and Dobolyi (2015) argued that a person's interpretation of a witness's verbal confidence is influenced by the diagnosticity of the features used to justify his or her identification. We tested this hypothesis in 2 experiments. Experiment 1 found that, relative to a confidence-only control, participants reduced their ratings of confidence when statements were justified using a facial feature that was shared by lineup members, but not when the feature was unique to the member chosen from the lineup. In Experiment 2, we found that participants integrated across the dimensions of witness confidence and accuracy, even when asked to make separate ratings. Altogether, the results suggest that people readily incorporate contextual information into their interpretations of witnesses' verbal expressions of confidence and evaluations of accuracy.