How stress affects our judgement
A good many of the choices that shape our lives are made at moments when we feel tense and on edge. Whether the matter in hand is our health, our money or our career, there are times when each of us has to sift through information while under pressure. Does that pressure sharpen the way we handle such information, though, or does it dull it?
To find out how the brain behaves when it is under strain, a fellow neuroscientist and I spent time at a number of mountain-rescue bases. No two shifts for these rescue crews are alike. There are calm stretches, during which the volunteers check over their ropes and stretchers, restock supplies and prepare food. Then there are the frantic days, full of call-outs in which lives hang in the balance: the crews are winched down to stranded walkers to treat severe injuries on the mountainside. That swing gave us an ideal setting in which to test how people use information once the pressure is on.
What we found was that a sense of danger set off a stress response which, for the rescue volunteers, actually eased the work of taking information in — provided that the information happened to be bad news.
The route to that conclusion ran as follows. Each volunteer was asked to put a figure on how likely they were to meet with 40 assorted misfortunes — from a road crash to having their identity stolen. We then fed back either encouraging news, that the odds were slimmer than they had assumed, or discouraging news, that the odds were greater, before asking them to revise their figures.
Most of the time human beings lean towards optimism, brushing aside gloomy information and welcoming the cheerful sort. That was exactly the response we saw while the volunteers were at ease. Once they were under stress, however, the picture changed. In that state they grew acutely alert to bad news — even bad news with no bearing whatever on their work, such as being told that identity theft was likelier than they had supposed — and adjusted their expectations accordingly. Good news, by contrast, was met no differently under stress than before, as when they were told the risk of identity theft was smaller than they had supposed.
The same tendency showed up back in the laboratory, this time among students told out of the blue that they must deliver a talk before an assessing panel — a talk that would be filmed and put online. Predictably, their cortisol readings shot up and their pulses quickened, and all at once they became sharper at absorbing unconnected but disturbing statistics on illness and crime.
A stressful episode sets in motion a change in the body that turns our attention towards warnings and towards whatever could go wrong. Scans of the brain show that this 'switch' goes hand in hand with a sharp rise in a learning-related neural signal, one that fires above all when we meet warning signs we did not expect — the sight of fear on another person's face, for example.
For our earliest ancestors, wiring of this kind may well have been a lifesaver. Hemmed in by predators, they stood to gain from any sharpening of their capacity to learn where the dangers lay. Where no threat was present, though, staying permanently on guard would only have squandered energy. A neural switch that raised or lowered the ability to take in warnings as surroundings shifted would therefore have had real value. Tellingly, those who suffer from clinical depression and anxiety appear stuck in the setting in which every negative message around them is soaked up.
Something else worth grasping is how quickly stress passes from person to person. When a colleague is on edge, the odds are that we will stiffen and grow tense as well. Nor do we have to share a room with someone for their feelings to steer how we behave. Research indicates that a feed full of positive posts — a photograph of a golden sunrise, say — makes us readier to put out cheering messages of our own, whereas a stream of negative ones, like grumbling about a slow-moving queue, prompts us to add negativity in turn.
In certain respects many of us now live as though under threat, forever braced to handle insistent emails and texts and to react to news alerts and online comments. One workplace-wellbeing survey found that continually glancing at your phone is bound up with stress. Put differently, a hardwired bodily response that evolution handed us so we could keep clear of starving predators is these days being set off by a post on a screen. Posting on social media, one study reports, does more to lift your pulse, bring on sweat and widen your pupils than most of the things you do in a day.
Because stress makes us dwell more on alarming messages, and because it also spreads at such speed, the two together can breed a collective fear that the facts do not always warrant. In the wake of a distressing public event — a natural disaster, perhaps, or a serious market crash — traditional and social media tend to fill with worrying reports that people cannot help noticing, and the effect is to make an existing danger look larger than it is. A dependable cycle thus takes shape: stress is set off and jumps from one person to the next, which for a while makes people more receptive to negative reports, which winds the stress up further. Holidays are called off though the catastrophe struck on the far side of the planet; shares are dumped when sitting tight would have been the wiser course. Encouragingly, though, upbeat feelings such as hope spread just as readily, and they carry real force in spurring people towards solutions. Once we appreciate how tightly a person's emotional state is tied to the way they handle information, we can shape our messages with more care and turn ourselves into thoughtful agents of change.
