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Default Assumptions—The Science Behind the Bias

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Unless we actively resist, unconscious bias can influence important decisions—especially those made in the voting booth, as science writer KC Cole explains.

When my daughter was six years old, we were having that standard parent conversation about what she’d be when she grew up. I told her, per the usual script, that she could be anything she wanted—including president of the United States! And she replied, with the kind of “duh” kids seem to reserve especially for clueless parents: “I can’t be president. I’m a girl.”

Where did she ever get such an impression? Easy: she’d looked at the pictures in books. Her “default assumption” was that a president had to be male (and no doubt, white).

Could Romney win the election because of our “default assumptions” about what presidents should “look like”? The answer is, of course, yes. Just because enough voters managed to overcome their ingrained (if unconscious) image of who's presidential in 2008 doesn't mean they’ll be able to do it again this year. Default assumptions make us do all kinds of dumb things.

Consider the following experiment:

You’re minding your own business when a passerby asks you for directions. You engage in a short conversation, which is briefly interrupted when two workers walk between you carrying a large door. A second later, you continue your conversation.

What you don’t notice is that the person asking directions is now someone else. Yep, that’s right. A different person took his place when the door passed between you. And you didn’t even notice. In fact, fully 50 percent of people who participated in this 1998 experiment by psychologist Daniel Simons were blind to the switch.

Why didn’t you notice such an obvious change? Because we see what we expect to see, and we don’t expect to see people we’re chatting with morph suddenly into other people. The “default assumption” is that they stay the same. And it’s powerful stuff.

The classic example of a default assumption is that old riddle about the man who drives his son to a baseball game, and the car gets stuck on the railroad tracks. A train comes, the father is killed, but the child survives, though in critical condition. When paramedics get him to the hospital, the doctor says: I can't operate on this boy, he's my son.

To this day, people come up with alien abductions to explain the riddle, rather than simply recognize that the doctor is the boy's mother. The default assumption says doctors are male.

Default assumptions can have serious consequences—from derailing careers in science to putting innocents on death row.

For example, a recent study out of Yale revealed that identical applications for a laboratory job were judged quite differently depending on whether the applicant was male or female. The mythical “John” received substantially more offers—and more money—than those from the mythical “Jennifer.”

A report several years ago from the National Science Foundation found a similar pattern: in order to be judged as productive as similar male applicants, women post docs had to publish an average of three more papers in prestigious journals, or 20 more in less-known publications.

Our default assumptions tell us scientists are male, so that’s what we’re primed to see.
And we don’t even know we’re doing it.

Try this experiment. Quickly picture in your mind’s eye: a doctor, an airline pilot, a CEO, a hedge fund manager, a newspaper editor, an engineer. Most people’s minds will quickly provide tall white men. When we go looking to fill one of these jobs, we’re usually unaware of what our brains have already decided. A small black woman, like a fat person or someone in a wheel chair, is highly unlikely to be chosen (or even apply).

Even if you personally know a small black woman who’s a CEO or a guy in a wheelchair who’s a physicist (and most of us at least know such people exist), you won’t revise your default assumption. You’ll consider these cases “exceptions.”

The same insidious assumptions explain in part why blacks are consistently found guilty more often than whites, even when the evidence is equally compelling, and especially if the jury is all white. Even more telling, the blacker the suspect’s skin, and the more stereotypically African his features, the more likely he is to be judged to be what Stanford psychologist Jennifer Eberhardt called “deathworthy.”

Eyewitness testimony is all but useless because it relies so heavily on these default assumptions (our brains have already decided who’s likely to be guilty). And also because it’s true that “they” (those not of our group) do “all look alike.”

Perhaps the most remarkable finding from the “switched passerby” experiment was that people had a much harder time distinguishing switches in people different from themselves—in other words, to middle-aged academics, construction workers tend to look alike, and vice versa. (This was also true of differences in age and race.)

Having default assumptions doesn’t make us bad, just human. We can’t get rid of them anyway. But we can recognize how they skew our judgment, and take steps to correct—just as you correct when you know your car pulls to the right.

For example, replace names with initials on job applications; make sure juries are diverse; have sufficient numbers of role models for minority groups in fields such as science so that the few stand-outs aren’t considered exceptions.

Because we make default assumptions about ourselves, too. A senior physicist once told me how hard it was to mentor the one African American man in his department. “If I get discouraged, I think of this long line of other Jewish physicists who succeeded; a black physicist doesn’t have that; it’s easy to give up and think, well, maybe I can’t do it.”

As black and female scientists become a more normal part of the landscape, default assumptions lose their power.

That kind of change won’t help anyone outwit the sneaky experimenter who wants to play mind games by switching people under your nose.

But it could help you outwit your own default assumptions in cases where it matters much so more.

A different version of this commentary appeared in the Los Angeles Times.

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