Despite Americans' penchant for self-help schemes that rely on positive thinking, it's the depressives who are more in touch with reality. Linda Besner considers the half-full approach to life, known as the optimism bias:
Current research shows that 80 percent of the world population thinks according to this pattern. Despite all available evidence, we don’t believe we will get cancer or get divorced, we all think we’re smarter and kinder than the average person, and we believe we have a better grip on reality than any of our friends do. … But our tendency to picture children rejoicing and jubilant friends hoisting us on their shoulders every time we run an errand is so pronounced that failing to do this—I can’t decide whether to laugh or cry here—is a sign of mild depression. It’s called "depressive realism." Sharot writes, "If you ask mildly depressed individuals what they expect in the upcoming month, they will give you a pretty accurate account. If you ask them about their longevity or the likelihood of having a certain illness, they will give you correct estimations."
The Dish 