CONTEXT: Early studies suggested that experienced clinicians simply generate more accurate diagnoses than those less experienced. However, more recent studies indicate that experienced clinicians may be subject to biases in formulating and confirming hypotheses that lead to inaccuracy. OBJECTIVES: The goal of this study was to identify factors associated with the ability to process information in ways that overcome premature closure and result in accurate diagnosis using a set of vignettes in which inconsistent information was introduced midway. METHODS: Seventy-five participants (25 Year 3 medical students, 25 internal medicine residents in their second year of residency and 25 internal medicine faculty) were recruited to solve each of four complex clinical vignettes. In each vignette, the first four rounds of information pointed toward a narrowing range of diagnostic possibilities, but patient information presented in and after the fifth round was inconsistent with prior findings. In addition to accuracy, outcome measures were length of differential diagnosis, certainty of diagnosis, persistence in data collection and tendency to switch diagnoses. RESULTS: There were no significant differences in diagnostic accuracy across the three groups, each of which differed in level of training. However, across experience levels, diagnostic accuracy was associated with the mean number of items in the differential, tendency to persist (e.g. to request a greater number of rounds of information), and openness to switch (e.g. to change the most likely diagnosis on receipt of disconfirming information). CONCLUSIONS: Level of training (i.e. clinical experience) was not associated with accuracy on this task. As faculty clinicians certainly have more knowledge than their junior counterparts, it is important to identify ways in which cognitive factors can lead to more or less persistence and openness, and to teach clinicians how to overcome tendencies associated with error.