What Do You Fail to Notice When You’re Hard at Work?

83% of two dozen radiologists who were searching for a lung nodule didn’t see the white outline of a standing gorilla that researchers had inserted into a computed tomography scan, even though it was 48 times the size of the average nodule, says a team led by Trafton Drew of Harvard Medical School. All of the participants reported seeing the gorilla when, after the experiment, they were shown the CT scan and asked if they noticed anything unusual about it. Past studies have demonstrated that people who are engaged in a task often fail to notice unrelated images and occurrences; the current finding suggests that this “inattentional blindness” affects even experts.