Participants in the new study who did good deeds -- or even just imagined themselves helping others -- were better able to perform a subsequent task of physical endurance. The research shows a similar or even greater boost in physical strength following dastardly deeds.
Results of the study are published in Social Psychological and Personality Science.
"Whether you're saintly or nefarious, there seems to be power in moral events," says Kurt Gray, a doctoral student in psychology at Harvard. "People often look at others who do great or evil deeds and think, 'I could never do that' or 'I wouldn't have the strength to do that.' But in fact, this research suggests that physical strength may be an effect, not a cause, of moral acts."
The conclusion comes from two studies. In the first, participants were given a dollar and told either to keep it or to donate it to charity; they were then asked to hold up a 5 lb. weight for as long as they could. Those who donated to charity could hold the weight up for almost 10 seconds longer, on average.
In a second study, participants held a weight while writing fictional stories of themselves either helping another, harming another, or doing something that had no impact on others. As before, those who thought about doing good were significantly stronger than those whose actions didn't benefit other people.
But surprisingly, the would-be malefactors were even stronger than those who envisioned doing good deeds.
The findings run counter to the notion that only those blessed with heightened willpower or self-control are capable of heroism, suggesting instead that simply attempting heroic or sinister deeds can confer personal power.
"Gandhi or Mother Teresa may not have been born with extraordinary self-control, but perhaps came to possess it through trying to help others," says Gray, who calls this effect "moral transformation" because it suggests that moral deeds have the power to transform people from average to exceptional.
Moral transformation has many implications. For example, it suggests a new technique for enhancing self-control when dieting: help others before being faced with temptation.
"Perhaps the best way to resist the donuts at work is to donate your change in the morning to a worthy cause," Gray says.
It may also suggest new treatments for anxiety or depression, he says: Helping others may be the best way of regaining control of your own life.