Influence of a single example on subsequent electrocardiogram interpretation

Background: Psychological theories of categorization based on prior instanc es predict that clinicians' accuracy in visual diagnosis may be influenced by prior similar cases. Purpose: To examine whether prior instructional examples influence electroc ardiogram (ECG) interpretation. Methods: Forty-one medical students and 27 family medicine residents were a llocated to 1 of 2 instructional sessions, where each ECG was accompanied b y a clinical scenario. In the subsequent test phase, new ECGs with a correc t diagnosis different from that in the instructional session were accompani ed by clinical scenarios reminiscent of the prior scenarios of the instruct ional session. Results: For residents, the prior scenarios resulted in a 50% loss of accur acy, from 46% accuracy without exposure to a similar scenario to 23% accura cy with exposure to a similar prior scenario. Students accuracy was equival ent under both conditions. Conclusions: Residents were influenced by the prior clinical scenarios in t heir subsequent ECG diagnoses. The same scenarios had an attenuated effect on the medical students.