Eyewitnesses' free-report verbal confidence statements are diagnostic of accuracy

We assessed recent policy recommendations to collect eyewitnesses' confidence statements in witnesses' own words as opposed to numerically. We conducted an experiment to test whether eyewitnesses' free-report verbal confidence statements are as diagnostic of eyewitness accuracy as their numeric confidence statements and whether the diagnostic utility of eyewitnesses' verbal and numeric confidence statements varies across witnessing conditions.

We hypothesized that eyewitnesses' verbal and numeric confidence statements are both significantly associated with identification accuracy among choosers and that their diagnostic utility holds across varying witnessing conditions.

In the first phase of the experiment, eyewitnesses (N = 4,795 MTurkers; 48.8% female; 50.8% male; .3% other; age M = 36.9) viewed a videotaped mock-crime and made an identification decision from a culprit-present or culprit-absent lineup. We manipulated witnessing conditions at encoding and retrieval to obtain varied levels of memory performance. In the second phase of the experiment, evaluators (N = 456 MTurkers; 35.5% female; 62.7% male .4% other; age M = 36.5) translated witnesses' verbal confidence statements to a numeric estimate and we used calibration and confidence-accuracy characteristic analyses to compare the diagnosticity of witnesses' verbal and numeric confidence statements across the two levels of memory performance.

Witnesses' verbal and numeric confidence statements were significantly and nondifferentially diagnostic of eyewitness accuracy for both choosers and nonchoosers, and their diagnostic utility held across variations in witnessing conditions.

These findings suggest the applied utility of collecting either verbal or numeric confidence statements from eyewitnesses immediately following an identification decision. (PsycInfo Database Record (c) 2021 APA, all rights reserved).