Research into diagnostic reasoning often focuses on diagnostic errors, while ignoring the also important concepts of overdiagnosis and cost of the diagnostic process. A popular theoretic model guiding studies on the subject is the dual process model in which cognitive errors play an important role. This paradigm is also used in the study of Mamede and colleagues, who studied the effect of disease specific knowledge on the occurrence of diagnostic errors due to availability bias in internal medicine residents. The study, which used case vignettes, is well set up but its experimental design cannot account for the influence of clinical context which limits its clinical value. Further research into this topic should be performed in actual clinical situations to provide more insight in how to improve diagnostic reasoning in medicine.