The prevalence effect in fingerprint identification: match and non-match base-rates impact misses and false alarms

The prevalence effect is a phenomenon whereby target prevalence impacts performance in visual search (e.g., baggage screening) and visual comparison (e.g., face-matching) tasks – people more often 'miss' infrequent target stimuli. The current study investigated prevalence effects in fingerprint identification – an important visual comparison task used in criminal investigations. Participants (N = 287) judged 100 fingerprint pairs where the prevalence of match trials was either 10% (low), 50% (equal), or 90% (high), and half received trial-level feedback on their performance. As predicted, low match prevalence increased errors on match trials (i.e., misses), whereas high match prevalence errors on non-match trials (i.e., false alarms) – but only when participants received feedback. These effects were largely driven by changes in bias (C), rather than sensitivity (d’). These results suggest that the combination of feedback and match prevalence can impact the types of errors that fingerprint examiners may make in practice.