LONDON, March 29 (UPI) -- Ignorance may be bliss for some, but a recent study in England found people who were most unsure whether they would receive an electric shock were more stressed about it than those who knew they would be shocked.
Researchers at University College London report uncertainty that something might happen, or waiting for it but not knowing when, causes more stress than being certain of what will happen, even if it's bad.
While stress has been important to human evolution as an internal warning of danger, the ability to heighten awareness with limited knowledge -- knowing an electric shock may come, but being unsure -- is an automatic protective measure.
Based on the study, the researchers said people with lower stress levels may have a better ability to manage and measure stress as a situational response.
"Using our model we could predict how stressed our subjects would be not just from whether they got shocks but how much uncertainty they had about those shocks," Dr. Archy de Berker, a researcher at University College London, said in a press release. "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. We saw exactly the same effects in our physiological measures -- people sweat more and their pupils get bigger when they are more uncertain."
For the study, published in the journal Nature Communications, the researchers recruited 45 participants to play a computer game requiring them to turn over rocks that could have a snake under them. The participants had to guess which rocks to turn over, with a goal of choosing those without a hidden snake. Each time a participant flipped a rock with a snake under it, the computer delivered a mildly painful electric shock.
In addition to slight differences tipping participants off to which rocks did and did not have snakes under them, the researchers changed the odds throughout the experiment as to whether a snake would be found at each rock.
The researchers monitored visible and physiological responses to the stress of picking rocks while trying to avoid snakes and shocks. In most cases, the researchers found participants closer to a 50 percent chance of shock were the most stressed, while shock risks closer to 0 percent or 100 percent caused less stress.
"When applying for a job, you'll probably feel more relaxed if you think it's a long shot or if you're confident that it's in the bag," said Dr. Robb Rutledge, a researcher at University College London. "The most stressful scenario is when you really don't know. It's the uncertainty that makes us anxious. The same is likely to apply in many familiar situations, whether it's waiting for medical results or information on train delays."