Want to be a more generous, cooperative person?

Don’t dwell on it. Be impulsive.

Our gut reaction is to give, according to a study published Wednesday by Harvard scientists who teased apart the workings of people’s minds when they’re asked to contribute to the greater good at their own expense. Only upon reflection do we become greedy.

The research lays bare a sort of tug-of-war that takes place in our minds between two cognitive systems: one that is quick and intuitive and spurs us to cooperate, and another that is slower, rational, and leads us to act self-interested.

“From a philosophical perspective, people have been asking for a long time: is cooperation our initial impulse? Or are we initially selfish and we have to control our selfish impulses?” said David Rand , a postdoctoral researcher at Harvard University who led the work. “People cooperate a lot, but not always. So, from a cognitive perspective: Why? Or how?”

To probe the question, the team borrowed tools and techniques from several fields. Working with evolutionary biologist Martin Nowak , who studies the evolution of cooperation, and psychology professor Joshua Greene , who studies the cognitive basis of moral judgments, Rand gave volunteers a series of scenarios in which they were given money and played games where they could earn more, depending on the choices they made about whether to cooperate with others.

The researchers repeatedly found that people acted most generously when they made snap decisions about how much to contribute, or were primed beforehand to recount a time in which their intuitions and emotions had guided them to a good decision. As people took more time to mull decisions over, or were asked to remember a time that they had benefitted because rational thinking or an emotional response had led them astray, they contributed less.

In one experiment, four participants were given 40 cents each and told that they could put as much money as they wanted into a common pot. The collective sum would be doubled and then dispersed evenly to all four people.

Those who made up their minds the quickest were markedly more willing to contribute than those who mulled it over for more than 10 seconds. When researchers introduced a time constraint, forcing some subjects to make up their minds rapidly and others to wait at least 10 seconds before deciding how much to contribute, they found again that those who had cogitated longest gave the least.

“People are asking you a question: ‘Will you contribute to a group?’ ... And what they’re showing is that the first impulse is to answer that question in the affirmative and say, ‘Yes, I will,’ ” said Daniel Kahneman, a Nobel laureate and author of the book, Thinking, Fast and Slow, which examines the two cognitive systems and the role they play in decision-making. “And then, when people think a bit more about it, they became a bit more salient. If the others do not contribute, then they’re suckers.”

The researchers involved in the study, published in the journal Nature, are quick to point out that the new work does not suggest that people are hardwired to do the right thing. Far from showing some “innate” predisposition to generosity, the research hints instead that people’s intuitive responses are associated with what they have learned -- through repetitive interactions in their real lives -- is advantageous.

In one study, researchers asked the participants if their everyday interactions with others were typically cooperative or uncooperative. Those who reported having mainly cooperative interactions were the ones who made quick decisions to contribute more and who gave less when they had more time to ponder the scenario. Among those who reported uncooperative interactions in daily life, there was no significant difference in how much they gave when they made a fast or more deliberate decision. The researchers said this suggests that their daily experience had shaped their intuitions.

Samuel Bowles, director of the behavioral sciences program at the Santa Fe Institute, said that there are obviously cases where the first impulse is not the “good” one. A large body of work in psychology spearheaded by Mahzarin Banaji, a psychology professor at Harvard, has shown that people have implicit biases that they may not even be aware of, causing them to unconsciously follow racial stereotypes despite not believing in them. When reacting to faces, for example, white people are quicker to associate positive adjectives with white faces and negative adjectives with African-American faces. In such cases, the more thoughtful, considered response -- to overcome any initial feeling of prejudice -- is the “good” one.

Bowles said that the research could have implications in the real world for how to design policies or incentives intended to encourage desired behavior. Paradoxically, Bowles said, when people are asked to do the “right” thing they may be predisposed by intuition to say yes. But if incentives are introduced, such as a monetary reward or a fine, people may begin to ignore their first response and weigh the costs and benefits, and this could result in more people acting selfishly.

The most striking example of this, he said, may be an Israeli study of day care programs. When fines were introduced as penalties if parents picked up their children late, more parents began to pick up their children late. Lateness, he said, became a commodity.

“In designing public policy, we have to find ways to make use of the incentives and constraints that do not demobilize or diminish the quite substantial moral commitments of populations to do the right thing,” Bowles said.