Proven: expecting something horrible can be horrible in itself.© Getty

The paralysing dread one feels before an injection or tooth extraction fires up some of the same brain regions involved in feeling pain itself, say researchers who subjected plucky volunteers to electric shocks. Their discovery supports the idea that distraction could ease a nasty wait.

Many people prefer to get an awful event over with sooner rather than later. But neuroscientists didn't know what was going on in our brains during this period of suspense, or exactly why we make this decision.

Gregory Berns of Emory University School of Medicine, Atlanta, Georgia, and his co-workers scanned the brains of 32 people while they waited for an electric shock to the foot, much like a spark from static electricity. During the experiment, people were offered a series of choices of the intensity of shock they would receive and when they would receive it.

When offered the choice of 'sooner' or 'later' for shocks of equal voltage, almost all the participants wanted to get the shock over with straight away. The team called these people 'mild dreaders'.

But nine people dreaded the shock so much that they chose a stronger blast sooner over a milder one later on. This group earned the label 'extreme dreaders'. Berns says that most people could probably if they were an extreme dreader from their everyday experience.

Focused feeling

Using functional magnetic resonance imagining, the team pinpointed regions of the brain that appeared to be the source of the dread. These areas were part of the brain's complex network for experiencing pain: specifically, it was the areas involved in paying attention to the body part about to experience pain, they found.

In extreme dreaders, such spots were more active, and their activity shot up earlier. This suggests that those people who intensely dreaded the shock were particularly focused on it, rather than that they were more fearful or anxious about it.

The study, published in Science¹, says that waiting is far from a passive time-killer for the brain, but rather can be just as engaging as the thing we are waiting for. "Expecting an emotional event is an emotional event," says Tor Wager of Columbia University in New York city, who has also studied the anticipation of pain.

Power of distraction

But the study "could in many cases be empowering", Wager adds, because it implies that actively drawing attention away from a dreaded public talk or operation could help assuage the discomfort of the wait. "It's good news because it means we can do something about it," Berns agrees.

The scientists don't know whether exactly the same process continues in the brain when we dread an event over several days or weeks, rather than a few seconds. And they have yet to probe the opposite process: when we lengthen the pleasant feeling of anticipation by putting off a good moment or meal.

The study also reinforces the broader idea that gut feelings and emotions, such as dread, can at any given time strongly sway the choices that we make, says George Loewenstein, an expert in decision-making at Carnegie Mellon University in Pittsburgh, Pennsylvania. "We're creatures of the moment," he says.

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• References

  1. Berns G.S, et al. Science, 312. 754 - 758 (2006).