Influence of a single example on subsequent electrocardiogram interpretation

Background: Psychological theories of categorization based on prior instances predict that clinicians' accuracy in visual diagnosis may be influenced by prior similar cases. Purpose: To examine whether prior instructional examples influence electrocardiogram (ECG) interpretation. Methods: Forty-one medical students and 27 family medicine residents were allocated to 1 of 2 instructional sessions, where each ECG was accompanied by a clinical scenario. In the subsequent test phase, new ECGs with a correct diagnosis different from that in the instructional session were accompanied by clinical scenarios reminiscent of the prior scenarios of the instructional session. Results: For residents, the prior scenarios resulted in a 50% loss of accuracy, from 46% accuracy without exposure to a similar scenario to 23% accuracy with exposure to a similar prior scenario. Students accuracy was equivalent under both conditions. Conclusions: Residents were influenced by the prior clinical scenarios in their subsequent ECG diagnoses. The same scenarios had an attenuated effect on the medical students.