Problems for clinical judgement: 2. Obtaining a reliable past medical history

ORDINARY HUMAN REASONING MAY LEAD PATIENTS to provide an unreliable history of past experiences because of errors in comprehension, recall, evaluation and expression. Comprehension of a question may change depending on the de finition of periods of time and prior questions. Recall fails through the l oss of relevant information, the fabrication of misinformation and distract ing cues. Evaluations may be mistaken because of the "halo effect" and a re luctance to change personal beliefs. Expression is influenced by social cul ture and the environment. These errors can also occur when patients report a history of present illness, but they tend to be more prominent with exper iences that are more remote. An awareness of these specific human fallibili ties might help clinicians avoid some errors when eliciting a patient's pas t medical history.