New research suggests that stress from fear of the unknown can be greater than the stress associated with knowledge of an outcome, even when the outcome is painful.
The research, published in Nature Communications, found that situations in which subjects had a 50 percent chance of receiving a shock were the most stressful while zero percent and 100 percent chances were the least stressful.
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
This is the first time that the effect of uncertainty on stress has been quantified, but the concept is likely to be familiar to many people.
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 co-author Dr. Robb Rutledge.
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.
Nevertheless, stress is not always negative and counterproductive. The study also found a potential benefit. People whose stress responses spiked the most at periods of greatest uncertainty were better at judging whether or not individual rocks would have snakes under them.
From an evolutionary perspective, our finding that stress responses are tuned to environmental uncertainty suggests that it may have offered some survival benefits
said senior author Dr. Sven Bestmann.”