On the difficulty of noticing obvious features in patient appearance

Medical students and experts were given head-and-shoulder photographs of patients, each showing a key feature of the patient's problem. Three quarters of these pictures were taken from textbooks. Noticing these supposedly obvious features It as difficult and strongly influenced by contextual factors. Both experts and students gained about 20% in diagnostic accuracy by having the key features verbally described for them, although these rr ere clearly visible on the photographs. Conversely, both experts and students reported seeing more of these features when the correct diagnosis rr as suggested to them. This facilitation resulted from art increase in sensitivity to depicted features, rather than a response bias. The properties of these features that allow such failures of noticing are discussed.