The confidence-accuracy relationship using scale versus other methods of assessing confidence

Abstract

Historically, researchers have collected eyewitness identification confidence using scales; however, in practice, eyewitnesses are more commonly asked for a verbal statement. In Experiment 1, participants viewed a simultaneous lineup and provided confidence in their own words, by explaining why they made their decision, or by selecting from statements made by real eyewitnesses, and then provided a scale rating (0-100%) or provided only the scale rating. In Experiment 2, participants viewed a sequential lineup and provided confidence in their own words followed by the scale rating or only the scale rating. Confidence predicted identification accuracy in all conditions, although verbal statements were highly variable and challenging to interpret. For example, only when scale-based confidence was high (80%+) did interpretation of the verbal confidence statement reliably align with scale-based confidence. These data highlight the complexity of verbal confidence statements and the need to establish meaningful boundaries for interpreting verbal confidence statements.