An early “inattention blindness” study demonstrated that half of the people viewing a group of students playing basketball failed to notice that a “gorilla” joined the game. In a newer study of “inattention blindness,” the experimenters inserted an image of a gorilla onto the upper right corner of a lung scan. It would be quite visible to anyone looking for it. Despite this, 83% of radiologists failed to notice it. Both studies are featured here.