Watch Out for Gorillas

Nobel Prize winning economist D. Kahneman proposes a simple puzzle. "A bat and a ball cost $1.10. The bat costs one dollar more than the ball. How much does the ball cost?" He states that most people come up with a quick answer - 10 cents.

The distinctive mark of this easy puzzle is that it suggests an answer that is intuitive, appealing, and wrong. Do the math and you'll see. If the ball costs 10 cents, then the total cost will be $1.20 (10 cents for the ball and $1.10 for the bat), not $1.10. The correct answer is 5 cents.

If you got the puzzle wrong, don't be discouraged. According to Kahneman's research, more than 50 % of students at Harvard, MIT, and Princeton gave the wrong answer. At public universities, over 80% of students failed the puzzle. Solving it doesn't depend on intelligence as much as it depends on our willingness to slow down, focus intently, and pay attention.

Kahneman describes also the “invisible gorilla test” - a team of 3 people dressed in black and a team of 3 people dressed in white passing a basketball to their teammates. The volunteers watching the game were told to keep track of how many times some basketball players tossed a basketball. While they did this, someone in a gorilla suit walked across the basketball court, in plain view, yet many of the volunteers failed even to notice the beast.

What the invisible gorilla study shows is that, if we are paying very close attention to one thing, we often fail to notice other things in our field of vision—even very obvious things. Our senses can play tricks on us - “inattentional blindness”. It can have serious implications, even life-threatening implications.

Three scientists at Brigham and Women’s Hospital in Boston wondered if expert observers are also subject to this perceptual blindness in diagnosing cancers. They recruited 24 experienced and credentialed radiologists—and a comparable group of naïve volunteers. They tracked their eye movements as they examined five patients’ CT scans, each made up of hundreds of images of lung tissue. Each case had about ten nodules hiding somewhere in the scans, and the radiologists were instructed to click on these nodules with a mouse. On the final case, the scientists inserted a tiny image of a gorilla into the lung. They wanted to see if the radiologists, focused on the nodules, would be blind to the strange and easily detectable gorilla.

The gorilla picture was about the size of a box of matches, or 48 times the size of a typical nodule. It faded in and out—becoming more, then less opaque—over a sequence of five images.  There was no mistaking the gorilla: If someone pointed it out on the lung scan and asked, What is that? – everyone would answer: That’s a gorilla.

After they were done scrolling through the images as much as they wanted, the scientists asked them three questions:

- Did that last trial seem any different?
- Did you notice anything unusual on the final trial? And finally:
- Did you see a gorilla on the final trial?

Twenty of the twenty four radiologists failed to see the gorilla, despite scrolling past it more than four times on average. And this was not because it was difficult to see: When shown the image again after the experiment, all of them saw the gorilla. 

Bottom line – it’s very easy for us mere humans to get deceived, to miss things and/or just not pay attention that well. The invisible gorilla shows up in many workplaces too. Being  focused on doing more we tend to miss some of the very important details that might change our outlook and approach towards those things we are so focused on.

When you read your Bible, take a step back. As Jesus says in Mathew 24:15  “whoever reads, let him understand”.

Take also a step back in your life and look for that gorilla.  Maybe your gorilla won’t be as easy to see it from the first attempt but there’s one there…if you look hard enough.