On the difficulty of noticing obvious features in patient appearance

Medical students and experts were given head-and-shoulder photographs of pa tients, each showing a key feature of the patient's problem. Three quarters of these pictures were taken from textbooks. Noticing these supposedly obv ious features It as difficult and strongly influenced by contextual factors . Both experts and students gained about 20% in diagnostic accuracy by havi ng the key features verbally described for them, although these rr ere clea rly visible on the photographs. Conversely, both experts and students repor ted seeing more of these features when the correct diagnosis rr as suggeste d to them. This facilitation resulted from art increase in sensitivity to d epicted features, rather than a response bias. The properties of these feat ures that allow such failures of noticing are discussed.