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Why We Hate Not Knowing for Sure

Recent research helps explain why our brains react so poorly to uncertainty.

I’m going to give you three options. You’ll only be OK with one of them, and one of the other two is going to nudge you a little closer to madness. Ready?

Here they are:

  1. I am not going to give you an electric shock.
  2. I am definitely going to give you an electric shock.
  3. I might give you an electric shock.
Image Point Fr/Shutterstock
Source: Image Point Fr/Shutterstock

While it goes without saying which one you’re OK with, which of the other two is starting to make the skin on your forearms itch a little? According to the results of a recently-published study, it’s probably not #2 (though that's not going to make me any friends). Rather, it’s what’s behind door #3 that stirs up the bats in your belfry, because when we’re facing outcomes imbued with uncertainty, it’s the fact that something bad might happen that gets us.

Researchers recruited 45 volunteers to play a computer game in which they turned over digital rocks that might have snakes hiding underneath. Throughout the game, they had to guess whether each rock concealed a snake, and when a snake appeared they received a mild but painful electric shock on the hand. Over the course of the game, they got better about predicting under which rocks they’d find snakes, but the game was designed to keep changing the odds of success to maintain ongoing uncertainty. In other words, they could only get marginally good at guessing before getting knocked off their game, again and again and again.

In the background, the researchers were running a sophisticated computational learning model to estimate the volunteers’ amount of uncertainty that any given rock was concealing a snake. At the same time, their stress was being monitored via instruments gauging pupil dilation and perspiration.

As it turned out, the volunteers’ level of uncertainty correlated in lockstep with their level of stress: If someone felt "certain" he or she would find a snake (100% probability that a snake lived there), their stress was significantly lower than if they felt like maybe a snake lived here. In both cases, they’d get a shock, but their stress was jacked with added uncertainty.

"Using our model we could predict how stressed our subjects would be not just from whether they got shocks but from how much uncertainty they had about those shocks," said lead author Archy de Berker of the UCL Institute of Neurology. "Our experiment allows us to draw conclusions about the effect of uncertainty on stress. It turns out that it's much worse not knowing you are going to get a shock than knowing you definitely will or won't."

What I like about this study is that it touches on a massive swath of life: We evolved to respond this way to uncertainty for excellent reasons—namely, the thing that might be lurking behind that rock or bush or up in that tree could harm, kill, or quite possibly eat us. Our brains are adaptively wired to react this way from way, way back in our ancestral history. Just because we’ve launched ourselves (and our brains) into this techno-socially advanced era doesn’t mean our brains are reacting less or even differently; they are just reacting to different threatening possibilities—some physical and many more perceptual.

Those perceptual, intangible uncertainties are arguably worse because they morph into different forms in our heads the more we think about them. The world has its monsters, no doubt, but we create many times more in the boundless space of our minds—not to mention the space of minds connected. And this has much to do with crippling fear and anxiety, numbing substance abuse, the appeal of authoritarian leaders, and a host of other topics for another day—all rooted back to the brain's insatiable craving for certainty.

The study was published in the journal Nature Communications.

You can find David DiSalvo at his website

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