On September 18, 2007, a few dozen neuroscientists, psychiatrists, and drug-company executives gathered in a khách sạn conference room in Brussels khổng lồ hear some startling news. It had to bởi with a class of drugs known as atypical or second-generation antipsychotics, which came on the market in the early nineties. The drugs, sold under br& names such as Abilify, Seroquel, and Zyprexa, had been tested on schizophrenics in several large clinical trials, all of which had demonstrated a dramatic decrease in the subjects’ psychiatric symptoms. As a result, second-generation antipsychotics had become one of the fastest-growing & most profitable pharmaceutical classes. By 2001, Eli Lilly’s Zyprexa was generating more revenue than Prozac. It remains the company’s top-selling drug.
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Many results that are rigorously proved & accepted start shrinking in later studies.Illustration by LAURENT CILLUFFO
But the data presented at the Brussels meeting made it clear that something strange was happening: the therapeutic power of the drugs appeared khổng lồ be steadily waning. A recent study showed an effect that was less than half of that documented in the first trials, in the early nineteen-nineties. Many researchers began khổng lồ argue that the expensive sầu pharmaceuticals weren’t any better than first-generation antipsychotics, which have been in use since the fifties. “In fact, sometimes they now look even worse,” John Davis, a professor of psychiatry at the University of Illinois at Chicago, told me.
Before the effectiveness of a drug can be confirmed, it must be tested và tested again. Different scientists in different labs need to repeat the protocols & publish their results. The test of replicability, as it’s known, is the foundation of modern research. Replicability is how the community enforces itself. It’s a safeguard for the creep of subjectivity. Most of the time, scientists know what results they want, and that can influence the results they get. The premise of replicability is that the scientific community can correct for these flaws.
But now all sorts of well-established, multiply confirmed findings have started lớn look increasingly uncertain. It’s as if our facts were losing their truth: claims that have been enshrined in textbooks are suddenly unprovable. This phenomenon doesn’t yet have sầu an official name, but it’s occurring across a wide range of fields, from psychology to ecology. In the field of medicine, the phenomenon seems extremely widespread, affecting not only antipsychotics but also therapies ranging from cardiac stents to lớn Vitamin E và antidepressants: Davis has a forthcoming analysis demonstrating that the efficacy of antidepressants has gone down as much as threefold in recent decades.
For many scientists, the effect is especially troubling because of what it exposes about the scientific process. If replication is what separates the rigor of science from the squishiness of pseudoscience, where do we put all these rigorously validated findings that can no longer be proved? Which results should we believe? Francis Banhỏ, the early-modern philosopher & pioneer of the scientific method, once declared that experiments were essential, because they allowed us to “put nature lớn the question.” But it appears that nature often gives us different answers.
Jonathan Schooler was a young graduate student at the University of Washington in the nineteen-eighties when he discovered a surprising new fact about language và memory. At the time, it was widely believed that the act of describing our memories improved them. But, in a series of clever experiments, Schooler demonstrated that subjects shown a face và asked lớn describe it were much less likely to recognize the face when shown it later than those who had simply looked at it. Schooler called the phenomenon “verbal overshadowing.”
The study turned hyên ổn into lớn an academic star. Since its initial publication, in 1990, it has been cited more than four hundred times. Before long, Schooler had extended the mã sản phẩm to a variety of other tasks, such as remembering the taste of a wine, identifying the best strawberry jam, and solving difficult creative puzzles. In each instance, asking people lớn put their perceptions inkhổng lồ words led lớn dramatic decreases in performance.
But while Schooler was publishing these results in highly reputable journals, a secret worry gnawed at him: it was proving difficult to replicate his earlier findings. “I’d often still see an effect, but the effect just wouldn’t be as strong,” he told me. “It was as if verbal overshadowing, my big new idea, was getting weaker.” At first, he assumed that he’d made an error in experimental design or a statistical miscalculation. But he couldn’t find anything wrong with his research. He then concluded that his initial batch of retìm kiếm subjects must have been unusually susceptible to lớn verbal overshadowing. (John Davis, similarly, has speculated that part of the drop-off in the effectiveness of antipsychotics can be attributed khổng lồ using subjects who suffer from milder forms of psychosis which are less likely lớn show dramatic improvement.) “It wasn’t a very satisfying explanation,” Schooler says. “One of my mentors told me that my real mistake was trying to replicate my work. He told me doing that was just setting myself up for disappointment.”
Schooler tried to lớn put the problem out of his mind; his colleagues assured hyên that such things happened all the time. Over the next few years, he found new retìm kiếm questions, got married và had kids. But his replication problem kept on getting worse. His first attempt at replicating the 1990 study, in 1995, resulted in an effect that was thirty per cent smaller. The next year, the kích cỡ of the effect shrank another thirty per cent. When other labs repeated Schooler’s experiments, they got a similar spread of data, with a distinct downward trend. “This was profoundly frustrating,” he says. “It was as if nature gave me this great result and then tried to lớn take it bachồng.” In private, Schooler began referring to lớn the problem as “cosmic habituation,” by analogy to lớn the decrease in response that occurs when individuals habituate to particular stimuli. “Habituation is why you don’t notice the stuff that’s always there,” Schooler says. “It’s an inevitable process of adjustment, a ratcheting down of excitement. I started joking that it was like the cosmos was habituating to my ideas. I took it very personally.”
Schooler is now a tenured professor at the University of California at Santa Barbara. He has curly blachồng hair, pale-green eyes, and the relaxed demeanor of someone who lives five sầu minutes away from his favorite beach. When he speaks, he tends lớn get distracted by his own digressions. He might begin with a point about memory, which reminds hyên ổn of a favorite William James quote, which inspires a long soliloquy on the importance of introspection. Before long, we’re looking at pictures from Burning Man on his iPhone, which leads us bachồng to lớn the fragile nature of memory.
Although verbal overshadowing remains a widely accepted theory—it’s often invoked in the context of eyewitness testimony, for instance—Schooler is still a little peeved at the cosmos. “I know I should just move on already,” he says. “I really should stop talking about this. But I can’t.” That’s because he is convinced that he has stumbled on a serious problem, one that afflicts many of the most exciting new ideas in psychology.
One of the first demonstrations of this mysterious phenomenon came in the early nineteen-thirties. Joseph Banks Rhine, a psychologist at Duke, had developed an interest in the possibility of extrasensory perception, or E.S.P.. Rhine devised an experiment featuring Zener cards, a special deck of twenty-five sầu cards printed with one of five different symbols: a card was drawn from the deông chồng và the subject was asked to lớn guess the symbol. Most of Rhine’s subjects guessed about twenty per cent of the cards correctly, as you’d expect, but an undergraduate named Adam Linzmayer averaged nearly fifty per cent during his initial sessions, và pulled off several uncanny streaks, such as guessing nine cards in a row. The odds of this happening by chance are about one in two million. Linzmayer did it three times.
Rhine documented these stunning results in his notebook & prepared several papers for publication. But then, just as he began to lớn believe sầu in the possibility of extrasensory perception, the student lost his spooky talent. Between 1931 and 1933, Linzmayer guessed at the identity of another several thous& cards, but his success rate was now barely above sầu chance. Rhine was forced khổng lồ conclude that the student’s “extra-sensory perception ability has gone through a marked decline.” And Linzmayer wasn’t the only subject to experience such a drop-off: in nearly every case in which Rhine và others documented E.S.P.. the effect dramatically diminished over time. Rhine called this trend the “decline effect.”
Schooler was fascinated by Rhine’s experimental struggles. Here was a scientist who had repeatedly documented the decline of his data; he seemed khổng lồ have sầu a talent for finding results that fell apart. In 2004, Schooler embarked on an ironic imitation of Rhine’s research: he tried to lớn replicate this failure to lớn replicate. In homage lớn Rhine’s interests, he decided to lớn test for a parapsychological phenomenon known as precognition. The experiment itself was straightforward: he flashed a phối of images to lớn a subject và asked hyên ổn or her lớn identify each one. Most of the time, the response was negative—the images were displayed too quickly khổng lồ register. Then Schooler randomly selected half of the images khổng lồ be shown again. What he wanted khổng lồ know was whether the images that got a second showing were more likely to have been identified the first time around. Could subsequent exposure have sầu somehow influenced the initial results? Could the effect become the cause?