Problem-oriented electronic medical records may have significant advantages over source-oriented organization of patient data. However, reorganizing data in this fashion may have unexpected consequences for the clinical decision-making process. To determine what these consequences might be, we conducted a pilot study using verbal protocols and video screen capture to characterize physician subjects' use of a traditional laboratory data display while reviewing unfamiliar inpatient cases. We found that subjects navigated to the laboratory display primarily to seek evidence confirming a result or problem identified elsewhere in the case. Additionally, 22% of the time subjects spontaneously reviewed anomalous findings and results related to other known problems. These results suggest that physicians have learned complex data acquisition behaviors for efficient interaction with source-oriented displays, and further study is needed to ensure that problem-oriented medical records do not lose the benefits of these behaviors.