Medical judgment and decision-making frequently occur under conditions of uncertainty. In order to reduce the complexity of diagnosis, physicians often rely on cognitive heuristics. Use of heuristics during clinical reasoning can be effective; however when used inappropriately the result can be flawed reasoning, medical errors and patient harm. Many researchers have attempted to debias individuals from inappropriate heuristic use by designing interventions based on normative theories of decision-making. There have been few attempts to debias individuals using interventions based on descriptive decision-making theories. Objectives: (1) Assess use of Anchoring and Adjustment and Confirmation Bias during diagnostic reasoning; (2) Investigate the impact of heuristic use on diagnostic accuracy; (3) Determine the impact of a metacognitive intervention based on the Mental Model Theory designed to reduce biased judgment by inducing physicians to 'think about how they think'; and (4) Test a novel technique using eye-tracking to determine heuristic use and diagnostic accuracy within mode of thinking as defined by the Dual Process Theory. Methods: Medical students and residents assessed clinical scenarios using a computer system, specified a diagnosis, and designated the data used to arrive at the diagnosis. During case analysis, subjects either verbalized their thoughts or wore eye-tracking equipment to capture eye movements and pupil size as they diagnosed cases. Diagnostic data specified by the subject was used to measure heuristic use and assess the impact of heuristic use on diagnostic accuracy. Eye-tracking data was used to determine the frequency of heuristic use (Confirmation Bias only) and mode of thinking. Statistic models were executed to determine the effect of the metacognitive intervention. Results: Use of cognitive heuristics during diagnostic reasoning was common for this subject population. Logistic regression showed case difficulty to be an important factor contributing to diagnostic error. The metacognitive intervention had no effect on heuristic use and diagnostic accuracy. Eye-tracking data reveal this subject population infrequently assess cases in the Intuitive mode of thinking; spend more time in the Analytical mode of thinking, and switches between the two modes frequently as they reason through a case to arrive at a diagnosis
