Sometimes, when people are doing something that demands their attention, they fail to notice that obvious, but unexpected, things have come into their line of sight. Psychologists call it inattentional blindness and think it happens when people are just so overloaded with stimuli they can’t devote their attention to any more.
To illustrate the phenomenon, researchers have done experiments where they ask people to watch a video of a basketball game. One team is wearing white shirts and the other is wearing black and the viewers need to keep count of how many passes the white team made. At one point during the game, a man in a gorilla suit walks onto the court, looks at the camera, thumps its chest and then leaves.
Almost everyone things they would notice something like this, but most of the time the experiment is done, half the viewers are so engaged in counting that they completely miss the gorilla!
Now, Harvard researchers have taken the “invisible gorilla” a step further. Rather than having people off the street watch a basketball game, they asked a group of experienced radiologists to look at a series of chest X-ray and locate nodules in the lungs.
A gorilla, 48 times the size of the average nodule, was inserted in the last case that was presented. Eighty-three percent of the radiologists did not see the gorilla. Eye tracking revealed that the majority of those who missed the gorilla looked directly at its location.
The takeaway from this? Even people who train for years to look for small abnormalities in images can miss something right in front of their face. Also, if you get small gorillas stuck in your lungs, you’re screwed. [Psychological Science]