The Canon (8 page)

Most of the time, Nolan said, the students are impressed and appreciate that the reporters did their jobs after all, a change of heart that so surprised me I had her repeat the words slowly and clearly and right into my tape recorder.

More to the point, when the students come across an example of ineptitude, they can articulate why they feel dissatisfied. "They started off being highly skeptical of everything they read, without knowing quite why," she said. "But as critical thinkers, they could back up their comments and misgivings with precise descriptions of what was in the original study and what was omitted."

I also like Bess Ward's method for converting her students from cynical derision to clinical precision. Ward is a professor of geosciences at Princeton University, and every year she tells her students, Pick a worry, any worry. She has them pose a question about an everyday concern of theirs, a personal habit or indulgence or preferred food that they may have heard or read a negative report about. Their task is to figure out, Should I really worry, or not? How big a risk am I taking if I continue to eat or act as I do, and how does this risk compare to other risky behaviors that I freely or of necessity engage in? Or should I feel guilty about my little luxuries because they may be harming others, or are bad enough for the environment that I can't quite justify them?

"I tell them, choose something that you relate to and that may sometimes nag at you from the background of your mind. Drinking a lot of coffee, or taking birth control pills, or eating tuna sandwiches, or bungee jumping," she said. "The idea is, look at the evidence and do a risk assessment."

For most of these concerns, the basic data points, the worry wartlets, are accessible on the Internet. The Environmental Protection Agency's Web page, for example, offers so-called reference doses for virtually every toxic chemical you're likely to encounter—scientific estimates of how much of the chemical you can be exposed to without suffering harm. Here you will find the average concentration of mercury in an average Charlie tuna presented as milligrams of toxin per kilogram of fish. You will also find how many milligrams of mercury a person can safely ingest per kilogram of his or her own body weight before needing to worry about achiness, bleeding gums, swelling, blindness, coma, and, well, I think I'll just go with the arugula salad, thanks.

Or let's say you're fretting, as one of Ward's students did, over the relative riskiness of a weekly manicure. When you're in a nail salon, you're breathing in all the fumes from nail lacquers and the solvents that remove them, an ambient nosegay only slightly more sensual than that of the elephant facility at the National Zoo. But is obnoxious necessarily noxious? On the EPA Web page, you will discover that nail polish and polish remover contain toluene, a moderately toxic petroleum extract that also happens to be moderately volatile—i.e., it evaporates easily into the air you'll soon be breathing. The EPA also offers figures on toluene concentrations in different workplace settings, including nail salons. Elsewhere on the Internet, you can gather results from inhalation surveys to see how much air the average person breathes in over the course of an hour, which is about how long you'll spend on a task that is literally as thrilling as watching paint dry. After analyzing these and other statistics, you may conclude, as the young student did, that her weekly manicures are reasonably harmless, but that she wouldn't want to work ten-hour shifts in a nail salon and that maybe she should give really big tips to the women who do.

Another surprising barrier to thinking scientifically is that we often believe we already understand how many things work, especially simple things we were supposed to have learned in one of our formative, single-digit grades. Even absent specific exposure to this or that kiddie science problem via a parent, a camp counselor, or the Professor on
Gilligan's Island,
we develop an intuitive grasp of physical reality, a set of down-to-earth, seemingly sensible explanations for everyday phenomena: why it's hot in the summer and cold in the winter, or what's going on when we throw a ball into the air. Sometimes these intuitive concepts are so comfortably lodged in our brains that if that tossed ball were to become a cartoon piano and fall on our heads, we'd pick ourselves up like a dazed Wile E. Coyote, shake the twinkling phosphenes from our eyes, and go back to our same misguided schemes for catching the bleep-bleep Road Runner.

Susan Carey, a professor of cognitive neuroscience at Harvard, has explored the ways that our lovingly cultivated and often erroneous models of physical reality can subvert understanding and impede our capacity to learn. She uses as an example a ball that has been tossed into the air and then falls back to the ground. Say you draw a picture of this trajectory, she said, with a series of balls in a steep arc to represent the ball rising upward, at midpoint in the air, and coming down again. You then ask people to draw arrows showing what sort of forces they think are acting on the ball during its trajectory—their strength and direction. The vast majority of people look at the picture and draw big force arrows pointing up while the ball is headed skyward, and big arrows pointing downward while the ball is descending. A sizable fraction of respondents, recognizing that gravity is acting on the ball during its entire voyage, will add little arrows pointing down next to the big arrows pointing up for the ascent portion of the curve. For the ball at its zenith, many will draw a little up arrow and a little down arrow that effectively cancel each other out.

It makes sense, doesn't it? Ball going up, force arrows pointing up; ball going down, force arrows plunging earthward. In fact, it makes so much sense that people believed exactly this model of motion for hundreds of years. There's even a name for it—the impetus theory, the idea that when something is in motion, a force, an impetus, must be keeping it in motion. As reasonable and as obvious as this theory seems, however, it is wrong. True, there was an upward force exerted on the ball when it first was thrust into the air, compliments of the pitcher. But once the ball has been launched, once it is in midexcursion, there is no more upward force acting on it. Once the ball is in the air, the only force acting on it is gravity. All those arrows on the diagram should be pointing down. If there were no gravity to worry about, a ball tossed upward would keep sailing upward, no further encouragement necessary. This is one of Isaac Newton's many brilliant productions, the famed law of inertia: an object at rest tends to stay at rest, unless induced by the nudge of a police officer's stick to get up off the park bench, this isn't the Plaza Hotel, you know; while an object in motion tends to stay in motion unless a force is applied to stop it. Yet even though we have heard about the law of inertia, and have seen the movie showing what happens when a jealous computer clips an astronaut's tether in the weightlessness of space—there he go-o-o-es—still we have trouble applying the idea of inertia to something in motion, and still we draw diagrams of ascending balls with upthrusting arrows.

"People come to science learning with a coherent, rather systematic theory of mechanical phenomena, and it's usually a variant of impetus theory," said Carey. "And often, as they learn about Newtonian theory, force, momentum, inertia, pressure, they simply assimilate the new information into their preexisting concepts." She and other researchers have found that even among people who have had a year of college physics, a high proportion will explain the ball's trajectory in impetus terms. "They hadn't undergone a conceptual change," she said. "The intuitive concepts they started with still held sway."

Sometimes a piece of knowledge learned early can make a powerful impression, can become an intuitive understanding that is then summoned forth in a valiant effort to explain something else. For example, researchers have shown that many people, on being asked why it is warm and sunny in the summer and cold and sullen in the winter, attribute seasonality to the comparative distance between Earth and the sun. They begin by stating a fact picked up at some point in elementary or high school—that Earth's orbit around the sun is not a perfect circle, but an ellipse. They then explain that, when Earth is closest to the sun on its ovoid track, we have summer; and when it is farthest away, it's time for road salt.

Walter Lewin, a professor of physics at MIT, showed me a video of Harvard seniors being asked, at their commencement ceremony, to explain why we have seasons. Again and again the young men and women, cucumber-confident in their caps and gowns, explained it as a matter of Earth being farthest from the sun in winter and closest in summer. The respondents weren't all art history or English majors, either, but included a few physics and engineering students as well.

Lewin, who is Dutch and therefore gratuitously tall, has an Einsteinian froth of whitish hair, a loping, electric style, and a facial expression often tuned to an impish, resigned incredulity. "The misconceptions of high school," he said, "can dog you for the rest of your life."

It's true that Earth's orbit is elliptical, he said, but only modestly so. Yet when the students try to explain in a drawing how the shape of our planet's orbit causes the seasons, they invariably exaggerate the eccentricity of the ellipse into something with the contours of a Tic Tac. Now they have a visual representation of how they view the seasons. You see way out here, at the farther elliptical tip of the orbit? That's winter. You see this tip, where we're squeezing toward the sun? That's summer. "They fail to ask the question, If this were the case, why, then, is it winter in the Southern Hemisphere when it's summer in the North, and vice versa?" said Lewin. "They can't shake the image of the all-powerful ellipse from their minds."

As it happens, Earth is slightly
farther
from the sun in July than it is in December, yet none of this matters. Seasonality is the result, not of orbital geometry, but of Earth's tilt: the fact that the globe is spinning on an axis that is tipped over 23 degrees relative to the plane of Earth's migration around the sun. As a result, sometimes the Northern Hemisphere points toward the sun and is bathed in a comparatively stronger and more direct blast of heat and light, and everybody living between Caracas, Venezuela, and Wood Buffalo, Canada, is advised to wear plenty of sunscreen, long-sleeved clothing, a sombrero, and a canvas tarp. Six months later, when Earth is at the opposite end of its lazy-Susan revolution, the Northern Hemisphere is tipped away from the sun, and it's the Southern Hemisphere's time to get braised.

Again, most people know about Earth's tilt, if for no other reason than their childhood exposure to that obligatory household prop, the four-color globe, on which half the countries have long since been renamed, redrawn, and overtaken by a military junta, and which was rarely used except for the purposes of spinning it around on its notably slanted axis until it squealed. Because the spinning was understood to explain why we have days and nights, however, the angle of the rotation was as likely to be erroneously lumped together with the day-night kernel of kiddie wisdom as with any explanation for snow days and summer vacations.

Nor is it necessary that we learn our misinformation in childhood to hang on to it as a toddler would a small, shiny choking hazard. Whether sizing up new acquaintances or seizing on novel ideas, we remain forever at the mercy of our first impressions. We hear an explanation for something we hadn't been exposed to before, it sounds good and tastes better, and—you didn't just swallow that thing, did you? Cindy Lustig, a professor of psychology at the University of Michigan, recently demonstrated the ease with which our mind makes up its mind about new things. She gathered together forty-eight of the standard academic research subjects—undergraduate students—and instructed them to make an association between two related words, like "knee" and "bend" or "coffee" and "mug."

On a follow-up test, she asked her subjects to change the association, so that instead of answering the "knee" cue with "bend," the person was to reply "bone"; for the coffee prompt, "cup" rather than "mug." OK, time for lunch. Later that day, Lustig divided the group of subjects in
two. Half were told to revert to the original association when confronted with the cue word. No problem: knee
bend,
coffee
mug.
The other group was asked to say whichever of their learned responses came to mind. Half of them would reply "bend" or "mug," and half "bone" or "cup." Good enough. Flip of the coin. Ah, but the next day, what then? When the random-answer subjects were again asked to say whatever response came to mind on hearing their cue words, a sizable majority conjured up their first tutorial, getting the bends, getting mugged. The earliest link, said Lustig, had become the brain's default setting.

Reporters know this tendency all too well, of the mind's readiness to make a quick connection and then seal it with an acrylic topcoat. I remember writing a story for the front page of the
New York Times
in 1991, about the spectacular discovery that we humans and other mammals have many hundreds of genes devoted to the production of odor receptors, the molecules studding the cells of our nasal passages that allow us to detect the thousands of aromas surrounding us. When I first heard the name of one of the smell researchers, Linda Buck, I immediately thought of another Linda with a similar surname, Linda Hunt, the New Jersey–born actress who won an Academy Award for playing a Chinese-Indonesian man. Well, both names are U-based, and you can
hunt
a
buck,
right? Ding-dong, connection made! Which is which? A wicked switch! I continued reporting the story. The hours flapped past. And when I finally got down to writing, I couldn't help but revert on cue to the earliest connection I'd made in the "Linda with the monosyllabic, rather bland last name" category, and I typed in Linda Hunt. Only at the last minute, right before the piece was to go to press, did I double-check the name against the journal article—and gasp at my error. Fortunately, I had time to make the change and save myself from prolonged humiliation. Linda Buck and her collaborator, Richard Axel, have since been awarded the Nobel Prize for their discovery, but there's still no Oscar in sight.