Decision-Making Under Stress: The Brain Remembers Rewards, Forgets Punishments
If you’re trying to make an important decision while the baby is crying, the boss is shouting on the phone and the cat has chosen this moment to think outside the box, you might want to take a breather and wait. A new review shows that acute stress affects the way the brain considers the pros and cons, causing it to focus on pleasure and ignore the possible negative consequences of a decision.
The research has implications for everything from obesity and addictions to finance, suggesting that stress may modify the way people make choices in predictable ways.
“Stress affects how people learn,” says Mara Mather, a psychology professor at the University of Southern California and the lead author of the review. “People learn better about positive than negative outcomes under stress.”
For example, two recent studies looked at how people learned to connect images, such as letters from an unfamiliar language, with either rewards or punishments. In one experiment, some of the participants were first stressed by having to give a speech and do difficult math problems in front of an audience; in the other, some were stressed by having to keep their hands in ice water. In both cases, the stressed participants remembered the rewarded material more accurately and the punished material less accurately than those whose testing was not preceded by stress.
This phenomenon is likely not surprising to anyone who has tried to resist eating cookies or smoking a cigarette while stressed out — at those moments, only the pleasure associated with such activities comes to mind. But the findings further suggest that stress may prompt relapse with a double whammy. Not only are rewarding experiences, like a drug high, remembered better, but negative consequences, like the crash afterward, are also less easily recalled.
Indeed, a 12-step program slogan — “Think it through” — seems to have been prompted by common experiences with this problem. The technique helps people in recovery to fight their urges by prompting them to consider the whole sequence of events that follows drinking or drug-taking, not just the good parts that are automatically replayed during craving.
This research also implies that programs that fight addiction by using punishment are unlikely to succeed. In fact, research suggests that treatments that use small rewards like merchandise or movie vouchers for clean urine samples work better than punitive treatments and that they actually save money. But programs that use positive reinforcement have traditionally been controversial because they are seen as rewarding addicts, a concept with which many critics disagree.
The new review paper also found that stress appears to affect decision-making differently in men and women. While both men and women tend to focus on rewards and less on consequences under stress, their responses to risk turn out to be different.
Here, researchers studied people playing a computer game in which they had to inflate balloons on screen. Bigger balloons earned more points, but each additional pump of air also raised the risk of popping the balloon and destroying its value entirely.
Men who had been stressed by the cold-water task tended to take more risk in this game — going for the extra pump — while women responded in the opposite way. That meant that the men ultimately earned more.
“What we found is that under stress, males are more likely to make risky choices and their decision strategies change so that they make their choices faster,” says Mather, “whereas females under stress become more conservative and actually make their choices slower in this risky decision-making context.”
The research suggests that in stressful situations in which risk-taking can pay off big, men may tend to do better; when caution is warranted, however, women will win. In the financial markets in the real world, several studies have found that women investors actually outperform men — and this is related to the fact that men tend to make more trades.
This tendency to slow down and become more cautious when decisions are risky might also help explain why women are less prone to addiction than men: they may more often avoid making the risky choices that ultimately harden into addiction.
The review didn’t examine the effects of chronic or early life stress on decision-making, but if, as in other areas, chronic stress magnifies the effects of acute stress, this may be another reason why excessive early life stress is linked with greater addiction risk.
The review [PDF] was published in Current Directions in Psychological Science.