Well Being

Is It Cancer? Or An Invisible Gorilla? Radiologists Can’t Tell

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Gorillas aren't known for being subtle creatures. If there was an angry gorilla around, you would probably know it. And if there was a picture of an angry gorilla somewhere it shouldn't be, you would probably notice that, too, right? Especially if said angry gorilla was sort of shaking his fist at you menacingly?

Well … no. You probably wouldn't. I'm not calling you a ninny or anything, it's just that in the lung scan photo above, the angry gorilla escaped the attention of 83% of the people who looked at it. People who were radiologists. People who were looking at this lung scan for abnormalities like cancerous nodules or angry fist-shaking gorillas.

Only that's the trouble: They weren't looking for angry fist-shaking gorillas. They were looking for normal lung-scan things. And human beings are famously bad for noticing even blatantly obvious things when they're concentrating on something else. So when researcher Trafton Drew asked a bunch of radiologists to look through a series of slides for signs of cancer, a large majority (83%) failed to notice our (non-cancerous) gorilla friend. According to NPR, this is due to what's known as “inattentional blindness.”

… when you ask someone to perform a challenging task, without realizing it, their attention narrows and blocks out other things. So, often, they literally can't see even a huge, hairy gorilla that appears directly in front of them.

It's not that the radiologists' eyes didn't spot the angry gorilla, but their brains had framed their task as “looking for cancer nodules.” The gorilla nodules just didn't compute.

“They look right at it, but because they're not looking for a gorilla, they don't see that it's a gorilla,” Drew told NPR. He and study co-author Jeremy Wolfe published their findings in in the January-February issue of the journal RadioGraphics.

Photo: Trafton Drew and Jeremy Wolfe

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