How Stress Influences Decision-Making

The set-up to a classic moral dilemma is simple: would you kill one person to save five?

You see a runaway trolley car hurtling down the tracks and if you pull a lever, you can switch the tracks, saving the five people that are standing unsuspectingly in its path.

The catch—and there’s always a catch in these thought experiments—is that switching tracks means you are responsible for the death of one person standing on Track 2.

The Brain

Psychologists talk about two brain pathways involved in decision-making: an emotional path, governed by the amygdala; and a rational one, governed by the prefrontal cortex.

The amygdala is involved when faced with difficult decisions that have emotional implications.

Neurobiology professor Larry Cahill edited an entire neuroscience journal dedicated to understanding how this affects men and women differently. For starters, men’s amygdala tend to be larger than women’s. They also work differently.

Psychologists report that while both men and women are concerned about the outcome of their decisions, especially in moral dilemmas, women tend to care much more about avoiding harm. This means that they are more likely to avoid “rational” decisions in favor of more “emotional” ones.

Research shows that women tend to want to avoid harm, so we are more likely to favor an “emotional” decision.

Does this help us make better decisions?

Well, that depends. If you are in a position where you are giving up something you want (for example, a job offer) because you are worried about your decision negatively affecting someone else (like your current boss), then it may not be a positive thing.

So how can you flip the switch in your brain and make a decision that favors you? The answer may lie in something unexpected, something you usually try to avoid: stress.

The Study

Over one hundred participants sat in my lab as they listened to different moral dilemmas. During some of these dilemmas, the participants were asked to stick their left hand in a bucket of ice water chilled to around 34°F for one minute. This task is designed to elevate stress levels.

A chain reaction happens in the brain once it detects a stressor (in this case, icy water is the physical stressor): the hypothalamus in the brain, which is responsible for our stress response, activates part of our autonomic nervous system (ANS), and releases adrenaline in preparation for a fight-or-flight response.

The Results

The physical stressor (ice water) appeared to flip a switch in their brains, and participants changed their initial emotional response to a more rational one. Now, when presented with the Trolley dilemma, they didn’t shy away from saving the five people. Instead, they were more likely to sacrifice one person for the greater good.

Why? For women, the default mode in tough emotional decisions is often to reduce harm, which relies on the amygdala. But with a stressor introduced, the amygdala is occupied, first with sounding the alarm in response to the stressor, then with deactivating after the stressor is removed.

This creates a window of opportunity for the prefrontal cortex, the rational part of the brain, to step in and take over. The prefrontal cortex sits in the front of our brain, aptly located, like a ruler taking charge of the rest of our sometimes impulsive and unruly cognitive functions.

The Takeaway

Stress in a short period (just one minute) overloads your emotional brain so you can flip the switch to using your rational brain in decision making.

A physical stressor, like sticking your hand in a bucket of ice for one minute can flip the switch off for your emotional brain. While your amygdala is busy focusing on the discomfort from the icy water, your prefrontal cortex has a window of opportunity to explore your options in a rational and objective manner.