The correct diagnosis required doctors to also see subtler cues, such as hyperinflation of the adjacent lobes. In marking the X-ray films, the experts picked out more specific features that were significant; they saw more clues to help them solve the puzzle of diagnosis. They also discriminated more finely. For example, the film showing tumors had a few hazy spots on it. The residents saw them as “general lung haziness” and figured they indicated fluid in the lungs, a sign of congestive heart failure. The experts saw correctly that each spot was a tumor.
