When it really comes down to it—when the chips are down and the lights are off—are we naturally good? That is, are we predisposed to act cooperatively, to help others even when it costs us? Or are we, in our hearts, selfish creatures?

This fundamental question about human nature has long provided fodder for discussion. Augustine’s doctrine of original sin proclaimed that all people were born broken and selfish, saved only through the power of divine intervention. Hobbes, too, argued that humans were savagely self-centered; however, he held that salvation came not through the divine, but through the social contract of civil law. On the other hand, philosophers such as Rousseau argued that people were born good, instinctively concerned with the welfare of others. More recently, these questions about human nature—selfishness and cooperation, defection and collaboration—have been brought to the public eye by game shows such as Survivor and the UK’s Golden Balls, which test the balance between selfishness and cooperation by pitting the strength of interpersonal bonds against the desire for large sums of money.

But even the most compelling televised collisions between selfishness and cooperation provide nothing but anecdotal evidence. And even the most eloquent philosophical arguments mean noting without empirical data.

A new set of studies provides compelling data allowing us to analyze human nature not through a philosopher’s kaleidoscope or a TV producer’s camera, but through the clear lens of science. These studies were carried out by a diverse group of researchers from Harvard and Yale—a developmental psychologist with a background in evolutionary game theory, a moral philosopher-turned-psychologist, and a biologist-cum-mathematician—interested in the same essential question: whether our automatic impulse—our first instinct—is to act selfishly or cooperatively.

This focus on first instincts stems from the dual process framework of decision-making, which explains decisions (and behavior) in terms of two mechanisms: intuition and reflection. Intuition is often automatic and effortless, leading to actions that occur without insight into the reasons behind them. Reflection, on the other hand, is all about conscious thought—identifying possible behaviors, weighing the costs and benefits of likely outcomes, and rationally deciding on a course of action. With this dual process framework in mind, we can boil the complexities of basic human nature down to a simple question: which behavior—selfishness or cooperation—is intuitive, and which is the product of rational reflection? In other words, do we cooperate when we overcome our intuitive selfishness with rational self-control, or do we act selfishly when we override our intuitive cooperative impulses with rational self-interest?

To answer this question, the researchers first took advantage of a reliable difference between intuition and reflection: intuitive processes operate quickly, whereas reflective processes operate relatively slowly. Whichever behavioral tendency—selfishness or cooperation—predominates when people act quickly is likely to be the intuitive response; it is the response most likely to be aligned with basic human nature.

The experimenters first examined potential links between processing speed, selfishness, and cooperation by using 2 experimental paradigms (the “prisoner’s dilemma” and a “public goods game”), 5 studies, and a tot al of 834 participants gathered from both undergraduate campuses and a nationwide sample. Each paradigm consisted of group-based financial decision-making tasks and required participants to choose between acting selfishly—opting to maximize individual benefits at the cost of the group—or cooperatively—opting to maximize group benefits at the cost of the individual. The results were striking: in every single study, faster—that is, more intuitive—decisions were associated with higher levels of cooperation, whereas slower—that is, more reflective—decisions were associated with higher levels of selfishness. These results suggest that our first impulse is to cooperate—that Augustine and Hobbes were wrong, and that we are fundamentally “good” creatures after all.

The researchers followed up these correlational studies with a set of experiments in which they directly manipulated both this apparent influence on the tendency to cooperate—processing speed—and the cognitive mechanism thought to be associated with this influence—intuitive, as opposed to reflective, decision-making. In the first of these studies, researchers gathered 891 participants (211 undergraduates and 680 participants from a nationwide sample) and had them play a public goods game with one key twist: these participants were forced to make their decisions either quickly (within 10 seconds) or slowly (after at least 10 seconds had passed). In the second, researchers had 343 participants from a nationwide sample play a public goods game after they had been primed to use either intuitive or reflective reasoning. Both studies showed the same pattern—whether people were forced to use intuition (by acting under time constraints) or simply encouraged to do so (through priming), they gave significantly more money to the common good than did participants who relied on reflection to make their choices. This again suggests that our intuitive impulse is to cooperate with others.

Taken together, these studies—7 total experiments, using a whopping 2,068 participants—suggest that we are not intuitively selfish creatures. But does this mean that we our naturally cooperative? Or could it be that cooperation is our first instinct simply because it is rewarded? After all, we live in a world where it pays to play well with others: cooperating helps us make friends, gain social capital, and find social success in a wide range of domains. As one way of addressing this possibility, the experimenters carried out yet another study. In this study, they asked 341 participants from a nationwide sample about their daily interactions—specifically, whether or not these interactions were mainly cooperative; they found that the relationship between processing speed (that is, intuition) and cooperation only existed for those who reported having primarily cooperative interactions in daily life. This suggests that cooperation is the intuitive response only for those who routinely engage in interactions where this behavior is rewarded—that human “goodness” may result from the acquisition of a regularly rewarded trait.

Throughout the ages, people have wondered about the basic state of human nature—whether we are good or bad, cooperative or selfish. This question—one that is central to who we are—has been tackled by theologians and philosophers, presented to the public eye by television programs, and dominated the sleepless nights of both guilt-stricken villains and bewildered victims; now, it has also been addressed by scientific research. Although no single set of studies can provide a definitive answer—no matter how many experiments were conducted or participants were involved—this research suggests that our intuitive responses, or first instincts, tend to lead to cooperation rather than selfishness.

Although this evidence does not definitely solve the puzzle of human nature, it does give us evidence we may use to solve this puzzle for ourselves—and our solutions will likely vary according to how we define “human nature.” If human nature is something we must be born with, then we may be neither good nor bad, cooperative nor selfish. But if human nature is simply the way we tend to act based on our intuitive and automatic impulses, then it seems that we are an overwhelmingly cooperative species, willing to give for the good of the group even when it comes at our own personal expense.

Are you a scientist who specializes in neuroscience, cognitive science, or psychology? And have you read a recent peer-reviewed paper that you would like to write about? Please send suggestions to Mind Matters editor Gareth Cook, a Pulitzer prize-winning journalist at the Boston Globe. He can be reached at garethideas AT gmail.com or Twitter @garethideas.