Visual memory effects on intraoperator study design: Determining a minimum time gap between case reviews to reduce recall bias

Objectives: The objective of this research was to determine test intervals between intraoperator case reviews to minimize the impact of recall. Methods: Three pathologists were presented with a group of 120 slides and subsequently challenged with a study set of 120 slides after 2-week and 4-week intervals. The challenge set consisted of 60 slides seen during the initial review and 60 slides previously unseen within the study. Pathologists rendered a diagnosis for each slide and indicated whether they recalled seeing the slide previously (yes/no). Results: Two weeks after having been shown 60 cases from a challenge set of 120 cases, the pathologists correctly remembered 26, 22, and 24 cases or 40% overall. After 4 weeks, the pathologists correctly recalled 31% of cases previously seen. Conclusions: Pathologists were capable of recalling from memory cases seen previously at 2 and 4 weeks. Recall rates may be sufficiently high to affect intraobserver study design.