Everybody has secrets. You do. I do. Maybe even the President of the United States does. For better or worse, science can’t much help in revealing the details of any particular secret. But it is gaining a better handle on the nature of secrets generally. For instance, according to a recent study by Michael Slepian, a professor of management at Columbia Business School, and two of his colleagues, the average person keeps thirteen secrets, five of which he or she has never shared with anyone else. If the President is anything like this average person, there’s a forty-seven-per-cent chance that one of his secrets involves a violation of trust; a sixty-plus-per-cent chance that it involves a lie or a financial impropriety; and a roughly thirty-three-per-cent chance that it involves a theft, some sort of hidden relationship, or unhappiness at work.

A great deal of research has explored the psychological effects that secrets have on their keepers—stress, anxiety, depression, loneliness, low self-esteem. But secrets can take a physical toll, too. In 2014, Clayton Critcher, a psychologist at the University of California, Berkeley, and Melissa Ferguson, a psychologist at Cornell, put volunteers in an interview situation and asked them to conceal their sexual orientation—for instance, by responding to questions about their dating preferences with phrases such as “I tend to date people who . . .” rather than “I tend to date women who . . .” Afterward, the secret-keepers performed seventeen per cent worse than control subjects on a spatial-intelligence test and, on a handgrip test, a third worse than they did before the experiment. (Control subjects showed no change.) In 2012, Slepian found that keeping a secret feels so burdensome that it alters how a person views his or her surroundings. Slepian had subjects recall (but not reveal) either a big personal secret, such as an infidelity, or a small one, such as a white lie. On a subsequent test, in which the subjects viewed images of hills, the people with “big” secrets estimated the hills to be steeper than the “small” secret-keepers did. And when told to toss a beanbag at a target a few feet away, they consistently overthrew it, judging the distance farther than it actually was.

Slowly but surely, secrets are spilling their secrets. But the jury’s still out on exactly how harmful they are. Andreas Wismeijer, a psychologist at Tilburg University, in the Netherlands, has argued that the murkiness derives in part from the fact that researchers are predisposed to explore the downsides of secrets. “The layman’s view that secrets are detrimental for our health,” Wismeijer wrote in a 2011 paper, “may have been so powerful that is has directly shined us in the eyes for decades.” From a health perspective, he concluded, secrets are “a clinical oxymoron.” A secret, basically.

Slepian, in his new paper, argues that it might help if we reconsidered how we think about secrets. A couple of years after his secrets-make-hills-steeper paper came out, other researchers were having trouble replicating its results. Slepian went back and ran it again, and initially he struggled, too. “So we started looking at it more closely,” he told me. “What we learned was that it really matters what people are thinking about.” When personal secrets were deemed “big” or “small” based on their content—that is, on a vague moral scale—the keepers’ estimates of distance and slopes were unaffected. But if a secret’s significance was instead defined in terms of how much time its keeper spent thinking about it, the landscape-bending effects reëmerged. “A conventionally big secret that may be preoccupying and all-consuming for one person, another person can shrug off,” Slepian said. “It became clear that what really determines whether these effects occur is how preoccupied people are by their secrets. When we saw that, it struck me that maybe we’ve been thinking about secrets in the wrong way.”

Traditionally, scientists have studied secrecy as a social act, as the willful hiding of information from others. According to this view, it’s the suppression of the secret—the keeping it in, the self-monitoring, and the tactical contortions that go with it—that exact a cost on the keeper. But Slepian argues that secrets cause suffering in other ways, too. Yes, there are occasions when you have to actively steer a conversation away from the rocks, like when you’re attempting to disguise from your office mates the fact that you’re looking for another job. But most of the time you’re by yourself with your secret, thinking about the many ways in which it could be discovered or you might accidentally let it slip. Slepian likes to quote the psychologists Julie Lane and Daniel Wegner, who, in a 1995 paper, wrote that “secrecy is something one can do alone in a room.” That’s not a minor aspect of secrecy, Slepian said; it’s the bulk of the experience.

This insight has led him and his colleagues, in their new paper, to propose “a new theory of secrecy.” Secrecy, as they see it, is less an activity than a state of being. We don’t keep secrets; we have them. And what’s harmful about a secret isn’t the content so much as the mind’s need to keep revisiting it and turning it over—not the murder itself but the incessant beating of the telltale heart.

To test out this theory, Slepian and his colleagues ran a series of studies. They presented more than fifteen hundred subjects with a “Common Secrets Questionnaire,” which listed thirty-eight categories of secrets, from social discontent and lying to self-harm and sexual infidelity, and asked which of these they hold or had ever held. The most commonly held secrets involved “extra-relational thoughts” and “sexual behavior.” Only thirty people said they’d never had any of the experiences on the list. The researchers went on to ask how frequently the subjects’ minds had wandered to those secrets in the previous month and how often they’d had to actively conceal them. The responses indicated that, by a margin of two-to-one or more, people dwelled on their secrets on their own time far more than in social situations. And the dwelling, more than the concealing, hurt their sense of well-being. By constantly chewing over a secret, Slepian suggested, people remind themselves of their own deceptiveness; they feel “inauthentic, disingenuous.”

Blessed are those, then, with more secrets than they care to remember. For the rest of us, Slepian recommends daylight. Secrets are largely solitary creatures and can be tamed with company. “Talking about it with another person will really go a long way,” he said. Melissa Ferguson, the Cornell psychologist who studied the cognitive and physical effects of concealing one’s sexual orientation, added that we shouldn’t lose sight of the costs of social secrets. She and Critcher began their study, she said, as a way of examining the potential impact of the military’s Don’t Ask Don’t Tell policy, which had been repealed a few years earlier. “What our work did was to open my eyes to some of the unintended consequences of certain policies,” she said. “There are plenty of situations where it would behoove a person to keep part of their identity secret, because revealing it could lead to violence. But it raises the question: Do you want to foster environments where people have to engage in secrecy in order to stay safe? I think we don’t.”