Nav: Home

Uncertainty can cause more stress than inevitable pain

March 29, 2016

Knowing that there is a small chance of getting a painful electric shock can lead to significantly more stress than knowing that you will definitely be shocked, finds a new UCL study funded by the Medical Research Council (MRC).

The study, published in Nature Communications, found that situations in which subjects had a 50% chance of receiving a shock were the most stressful while 0% and 100% chances were the least stressful. People whose stress levels tracked uncertainty more closely were better at guessing whether or not they would receive a shock, suggesting that stress may inform judgements of risk.

The experiment involved 45 volunteers who played a computer game in which they turned over rocks that might have snakes under them. They had to guess whether or not there would be a snake, and when there was they received a mildly painful electric shock on the hand. Over time they learned which rocks were most likely to harbour snakes, but those odds changed throughout the experiment, generating fluctuating levels of uncertainty.

Participants' uncertainty that any individual rock would have a snake under it was estimated from their guesses using a sophisticated computational model of learning. This uncertainty matched the stress levels reported by participants, which was also tracked using measurements of pupil dilation and perspiration.

"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," explains lead author Archy de Berker (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. 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," says co-author Dr Robb Rutledge (UCL Institute of Neurology and Max Planck UCL Centre for Computational Psychiatry and Ageing Research). "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."

Stress in the modern world is often seen as a negative and counterproductive response, but 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 benefit," explains senior author Dr Sven Bestmann (UCL Institute of Neurology). "Appropriate stress responses might be useful for learning about uncertain, dangerous things in the environment. Modern life comes with many potential sources of uncertainty and stress, but it has also introduced ways of addressing them. For example, taxi apps that show where a car is can offer peace of mind by reducing the uncertainty about when it will arrive. Real-time information boards at bus stops and train platforms perform a similar role, although this can be undermined by unspecified delays which cause stress for passengers and staff alike."
-end-


University College London

Related Stress Articles:

Measuring stress around cells
Tissues and organs in the human body are shaped through forces generated by cells, that push and pull, to ''sculpt'' biological structures.
Cellular stress at the movies
For the first time, biological imaging experts have used a custom fluorescence microscope and a novel antibody tagging tool to watch living cells undergoing stress.
Maternal stress at conception linked to children's stress response at age 11
A new study published in the Journal of Developmental Origins of Health and Disease finds that mothers' stress levels at the moment they conceive their children are linked to the way children respond to life challenges at age 11.
A new way to see stress -- using supercomputers
Supercomputer simulations show that at the atomic level, material stress doesn't behave symmetrically.
Beware of evening stress
Stressful events in the evening release less of the body's stress hormones than those that happen in the morning, suggesting possible vulnerability to stress in the evening.
More Stress News and Stress Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Rethinking Anger
Anger is universal and complex: it can be quiet, festering, justified, vengeful, and destructive. This hour, TED speakers explore the many sides of anger, why we need it, and who's allowed to feel it. Guests include psychologists Ryan Martin and Russell Kolts, writer Soraya Chemaly, former talk radio host Lisa Fritsch, and business professor Dan Moshavi.
Now Playing: Science for the People

#537 Science Journalism, Hold the Hype
Everyone's seen a piece of science getting over-exaggerated in the media. Most people would be quick to blame journalists and big media for getting in wrong. In many cases, you'd be right. But there's other sources of hype in science journalism. and one of them can be found in the humble, and little-known press release. We're talking with Chris Chambers about doing science about science journalism, and where the hype creeps in. Related links: The association between exaggeration in health related science news and academic press releases: retrospective observational study Claims of causality in health news: a randomised trial This...