Electric shocks are more painful when they are uncertain than when they are definitely coming, a new study finds.
It confirms just how stressful uncertainty can be compared with knowing what is coming.
Dr Robb Rutledge, one of the study’s authors, explained:
“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.
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.”
For the research, people played a game during which they were sometimes given mild electric shocks.
Sometimes people could predict when they were going to get a shock, other times they could not.
It was the unpredictable nature of the shocks which made them more stressful, the results showed.
Mr Archy de Berker, the study’s first author, said:
“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.”
Dr Sven Bestmann, one of the study’s co-authors, said:
“From an evolutionary perspective, our finding that stress responses are tuned to environmental uncertainty suggests that it may have offered some survival benefit.
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.”
The study was published in the journal Nature Communications (de Berker et al., 2016).
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