A cynic, Ambrose Bierce remarked in his “Devil’s Dictionary,” is “a blackguard whose faulty vision sees things as they are, not as they ought to be.” In the century that has elapsed since Bierce’s death, science has caught up with him. Cynicism, in all its guises, really may make us see the world more realistically—though at a high personal cost.

The phenomenon, which psychologists call “depressive realism,” was first identified by Lauren Alloy and Lyn Abramson, psychologists at Northwestern and the State University of New York at Stony Brook, respectively, who were studying the illusion that people often have of being in control when, in reality, they are not. In 1979, they took two groups of college students—one depressed, one not—and had them estimate how much control they had over a green light that would either turn on or not when they pressed a button. In reality, there was never a perfect correlation between the action and the event. The light would sometimes turn on when the student pressed the button, and sometimes when he didn’t. What varied from student to student was the frequency with which the action corresponded with a result. The researchers found that the depressed individuals were much better at identifying those instances when they had little control over the outcomes, while the non-depressed students tended to overestimate their degree of influence over the light.

The difference became even more interesting when Alloy and Abramson added money into the experiment. In some cases, the light was linked to losing money. Participants started out with five dollars and gradually lost it, quarter by quarter, as the light didn’t respond to their actions. In the other cases, the light signalled financial gain; participants started with nothing but received a quarter each time the light went on. At the end, each person in the first situation emerged having lost five dollars, and each in the second having won five dollars.

When the researchers asked the participants how much control they thought they’d had throughout the experiment, those who weren’t depressed reported having significantly more control than they actually had—but only when they won. When they lost, they estimated that they had much less control than was the case. The depressed participants, on the other hand, were far more accurate in their judgments across the board. Depression, Alloy and Abramson concluded, had prevented an unwarranted illusion of control when someone won—and had provided a sense of responsibility when someone lost. In the years since Alloy and Abramson’s initial studies, depressive realism has also been shown to arise from general pessimism and, yes, from cynicism.

By 1992, Alloy and Abramson had replicated their findings in numerous contexts and could take the logic further. Not only were depressed individuals more realistic in their judgments, they argued, but the very illusion of being in control held by those who weren’t depressed was likely protecting them from depression in the first place. In other words, the rose-colored glow, no matter how unwarranted, helped people to maintain a healthier mental state. Depression bred objectivity. A lack of objectivity led to a healthier, more adaptive, and more resilient mind-set. In a 2004 meta-analysis, Abramson and colleagues at the University of Wisconsin at Madison confirmed that the positivity bias held firm both internationally and in large non-student samples. The over-all effect, they concluded, “may represent one of the largest effect sizes demonstrated in psychological research on cognition to date.”

Why would that be the case? As it turns out, the way we explain the world can have very real effects on our physical and emotional well-being—both positive and negative. It’s a phenomenon that the Harvard University psychologist Daniel Gilbert has called the “psychological immune system,” a feedback loop between how we think and how we feel. If we think more optimistically, we tend to feel better, which in turn makes us think more optimistically.

The notion that our outlook on life is connected to our well-being is not a new one. In the nineteen-sixties, the University of Connecticut psychologist Julian Rotter proposed that we could view external events in one of two lights: either we controlled them or they were the result of something in the environment. He found that successful people tended to follow the same patterns. They took credit for successes, and they reasoned away negative events.

A decade later, the University of Massachusetts psychologists Bobbi Fibel and W. Daniel Hale realized that the effect went even further: when you thought you’d do well over all—a mind-set that they termed a “generalized expectancy of success”—you were more likely to be shielded from negative life events. It didn’t matter whether you were in control; what mattered was your belief that you had good things coming to you. Of course, optimistic people still get hit by lightning and run over by cars—and too much optimism can result in the highly negative repercussions that often accompany overconfidence, from ruinous financial choices to disastrous political missteps. But, Fibel and Hale found, positive expectations generally lead to positive results.

Most recently, the psychologists Michael Scheier and Charles Carver have taken the insight further still: the positive buffer comes from neither simply control nor expectation alone. Instead, it’s your general outlook on life, or, as they call it, your “life orientation.” Their Life Orientation Test, or LOT, measures how a person responds to a set of statements that range from “I hardly expect things to go my way” to “In uncertain times, I usually expect the best.” Positive responses are associated with generalized success and negative responses are related to depression and helplessness. In a [review](file://localhost/n%20the%20Power%20of%20Positive%20Thinking/%20The%20Benefits%20of%20Being%20Optimistic) of the health benefits of an optimistic life outlook, they found that a more positive—even if misguided—outlook was connected to an improved ability to deal with stressful events. What’s more, it prevented the onset of depression to begin with: in a study of pregnant women who were followed throughout their last trimester and during the first three weeks after they gave birth, initial levels of optimism predicted the lower likelihood of postpartum depression. Likewise, college students who scored high on measures of optimism in a number of psychological assessments when they first arrived at school were doing better three months later. The effects can go beyond the purely mental. Men who were more optimistic prior to coronary-artery bypass surgery were less likely to suffer a heart attack during the operation and recovered more quickly afterward.

In a review of the field that’s due out this month, Carver and Scheier have further expanded their initial findings to show that increased optimism, after controlling for other factors, also leads to improved career success, strengthens friendships and marriages, protects against loneliness later in life, lowers the risk of heart disease and mortality in women over an eight-year period, protects against strokes, helps to reduce the need for rehospitalization following surgery, and improves sleep quality in children. In all cases, optimism serves as a shield, allowing us to see the world in a light that is more conducive to our own mental and physical well-being.