Which way to go? Not knowing the outcome can be tougher than the outcome itself.
Now, research published in Nature Communications suggests that knowing that something bad is going to happen is better than not knowing whether it will happen or not.
Findings show that a small possibility of receiving a painful electric shock causes people more stress than knowing for sure that a shock was on the way.
Researchers from University College London (UCL), in the UK, enlisted 45 volunteers to play a computer game, which involved turning over rocks under which snakes might lurk.
The aim was to guess whether or not there would be a snake. Turning over a rock with a snake underneath led to a small electric shock on the hand.
As the participants became more familiar with the game, the chance of a particular rock harboring a snake changed, resulting in fluctuating levels of uncertainty.
Stress levels match levels of uncertainty
An elaborate computer model measured participants' uncertainty that a snake would be hiding under any specific rock.
To measure stress, the researchers looked at pupil dilation, perspiration and reports by participants.
The higher the levels of uncertainty, say the findings, the more stress people experienced. The most stressful moments were when subjects had a 50% chance of receiving a shock, while a 0% or 100% chance produced the least stress.
People whose stress levels correlated closely with their uncertainty levels were better at guessing whether or not they would receive a shock, suggesting that stress may help us to judge how risky something is.
Lead author Archy de Berker comments:
"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."
While many people will find the concept familiar, this is the first time for research to quantify the effect of uncertainty on stress.
Coauthor Dr. Robb Rutledge notes that people who are applying for a job will normally be more relaxed if they know they either will or will not get the job. "The most stressful scenario," he says, "is when you really don't know. It's the uncertainty that makes us anxious."
Stress: a survival strategy?
Dr. Rutledge points out that the same principle applies whether a person is waiting for medical results or delayed transportation.
Fast facts about stress
- Symptoms of stress include powerlessness and difficulty making decisions
- Stress can help you develop coping strategies for life
- To minimize stress, eat well, keep active and avoid drugs and alcohol.
Senior author Dr. Sven Bestmann explains that modern life entails many potential sources of uncertainty and stress, but it also provides ways of dealing with them.
An example of modern stress-busting tools includes real-time information of the sort available through taxi apps, which can decrease stress levels by tracking the taxi's location, giving a waiting customer the chance to calculate how soon it will arrive.
Previous studies have suggested that inability to control a situation also plays a role.
But stress is not a new phenomenon; and while current thinking focuses mainly on the negative impact of stress, there may be benefits, too.
In the experiment, those who experienced the greatest stress at moments of high uncertainty were also better able to judge whether or not a particular rock was hiding a snake.
The researchers note that, in terms of evolution, the fact that stress responses correlate with environmental uncertainty suggests that stress may contribute to survival.
"Appropriate stress responses," says Dr. Bestmann, "might be useful for learning about uncertain, dangerous things in the environment."
Medical News Today recently reported that stress before pregnancy can affect birth weight.