The Invisible Gorilla Effect

invisible gorilla

Remember the invisible gorilla video?

In an experiment popularized by the book of the same name, volunteers were told to keep track of how many times a basketball was passed between players. While the ball was being tossed, someone in a gorilla suit walked between them in plain view. Very few people noticed the gorilla because they were so focused on counting the passes.

The invisible gorilla study is the most famous example of a phenomenon called inattentional blindness. When we pay close attention to one thing, we often fail to notice other things – even if they are obvious. The authors of the book modified the original video to reinforce the point. Watch the updated video to see if you notice anything unusual:

If you’re like most people – including me – you didn’t notice the person leaving the game or the background curtains change color. You had inattentional blindness.

One thing has always bothered me about the gorilla experiment. Counting basketball passes is not a real-life task and the participants have no training in it. It’s possible they are easily fooled or just lazy. Would the same thing happen to experts?

A recent study from Brigham and Women’s Hospital confirms experts suffer from inattentional blindness and raises some uncomfortable questions in the process. The scientists asked experienced radiologists to identify white nodules within five CT scans made up of hundreds of images of lung tissue – a process used to identify potential lung cancer.  In one of the scans, the scientists inserted an image of a gorilla almost 50 times the size of a nodule.

Despite its relatively large size and its incongruous presence in the CT scans, only four of the 24 radiologists noticed the gorilla. It’s not that it was difficult to see; eye-tracking data showed clearly that the radiologists looked right at it. And when later told to look for a gorilla, nearly everyone found it.

The scientists repeated the experiment on untrained volunteers and none noticed the gorilla. Not surprisingly, the radiologists were also much better at spotting the warning signs of lung cancer.

The confirmation that expert observers suffer from inattentional blindness raises some troubling questions. By training radiologists to identify white nodules, are they more likely to miss other life-threatening anomalies? Could the same issues pertain to other expert observers like MRI technicians, air traffic controllers, and police officers?

That’s one scary gorilla.

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11 Responses to The Invisible Gorilla Effect

  1. Sandra Harriette February 10, 2013 at 3:36 pm #

    I laughed so hard!

  2. Sandra Harriette February 10, 2013 at 3:38 pm #

    Now, about the medical implications: that’s not funny. It was the fact that people did not see that life size gorilla the first time. I did although I didn’t notice the curtain….I have to admit.

  3. Allison @ The Book Wheel February 10, 2013 at 5:09 pm #

    I remember watching this in one of my classes. I definitely did not see the gorilla at first!

  4. Trevor Nagle, ABD February 11, 2013 at 5:40 am #

    Reblogged this on Leadership Musings of a Skeptical Positivist and commented:
    “Inattentional Blindness.” It’s potentially an issue for all of us in our professional roles and in our relationships in our personal life. What kinds of things can we do to train ourselves out of this tendency?

  5. Mark Yolton (@MarkYolton) February 11, 2013 at 6:45 am #

    An everyday application: One of the most common excuses given after a driver pulls out into the path of a motorcycle and causes an accident is “I never saw him!” (even with his headlights and running lights on, loud pipes, shiny chrome, and all the rest…). The drivers stopped at the intersection, carefully looked both ways, and pulled out directly into an oncoming rider. I suspect that “inattentional blindness” is the cause… they were looking for cars and trucks, not motorcycles…

  6. Anonymous February 11, 2013 at 1:40 pm #

    This exact piece was on NPR today

    • Jonathan February 11, 2013 at 1:59 pm #

      I posted this on Sunday and they ran the piece on Monday. Imitation is the sincerest form of flattery.

  7. Reblogged this on gabriel catalano and commented:
    The invisible gorilla study is the most famous example of a phenomenom called “inattentional blindness.” When we pay close attention to one thing, we often fail to notice other things – even if they are obvious.

  8. plugnetsolutions February 19, 2013 at 4:31 pm #

    Reblogged this on plugnet.

  9. aferrari00 March 12, 2013 at 8:37 am #

    Reblogged this on Alessandro C. E. Ferrari and commented:
    Quale è il gorilla che Vi sta sfuggendo nella Vostra organizzazione?


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