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In the wake of San Francisco's devastating 1906 earthquake, as survivors sifted through rubble and fires raged, the city's men and women responded to the chaos in an unusual way: by getting married.

The magnitude 7.9 quake demolished the city, killed 3,000 people, and left hundreds of thousands homeless. But in the 10 days after the disaster, marriages in San Francisco and Alameda County surged to four times the normal rate. The Oakland Tribune observed "young couples scrambling about among the ruins trying to find where marriage licenses were issued," and The Louisville Courier-Journal remarked that couples were being "earthquaked into marriage."

Getting hitched might seem like an odd reaction to a disaster. But in an uncertain time, these couples found something stable in each other. As psychological studies show, uncertainty triggers a deep craving in all of us for stability, and that can motivate people to do strange things.

"Unrelated threats can raise our distaste for ambiguity in general," says Jamie Holmes, who recounted the San Francisco wedding surge in a new book about how people experience uncertainty called, "Nonsense: The Power of Not Knowing." Several studies suggest that natural disasters, including Hurricane Hugo in 1989 and the Japanese tsunami in 2011, led to a spike in marriages or divorces -- both of which are a form of certainty, Holmes says.

In his book, Holmes describes how the human brain works in hidden and surprising ways to mitigate confusion in the world around us. In order to manage the avalanche of information that our senses are absorbing at all times, our brains work to find patterns, simplify information, and look for clarity, he says. That allows us to be able to make decisions and act.

But sometimes in the rush to make order of the world, our brains jump to unwarranted conclusions — taking in the myriad of information around us and deducing something that just isn't quite right.

There are a lot of interesting illustrations of how our brains contort themselves. One fascinating one is "the McGurk effect," an auditory illusion demonstrated in the video below:

Do you hear the difference? This simple auditory illusion will challenge the way you perceive the world. (Daron Taylor/TWP)

Did you hear two different sounds in the video? Actually, the sound stays constant throughout. But when the image changes, the sound that you perceive does, too. What you're seeing doesn't match what you're hearing, and your brain overrides your sense of sound to make the information match.

"It shows the senses co-evolved, but it also shows our expectation that the sound we hear and the shape of moving lips will match," says Holmes. "And it shows how aggressively our minds make sense of the world and reduce it to fit our expectations."

I. Why confusion makes some people creative and other people crazy

Not everyone has the same impulse when it comes to ambiguity. Some people are very uncomfortable with confusion, and their minds jump to quick decisions in the face of uncertainty. Others are content to be confused a while, and may even find it makes them more creative. Even with this article, some may have read the ambiguous headline and been intrigued -- while others may have felt annoyed or daunted.

Psychologists describe the degree to which people seek out certainty as their "need for closure." This trait varies not just from person to person, but also with environmental factors, like fatigue, time pressure and stress.

The need for closure doesn’t have anything to do with intelligence, but it can have a powerful influence on your behavior -- including your capacity to innovate, your predilection for stereotyping, and your ability to make decisions in times of crisis. You can take a quick quiz to test your own need for closure by clicking here.

[Quiz: How comfortable are you with uncertainty?]

A high need for closure isn't necessarily a bad thing. You may just be the type of person who likes to make plans and avoid surprises. However, the need for closure can lead to two major pitfalls in decision making, says Holmes.

The first is what psychologists call the "urgency effect," which is basically the tendency to jump to conclusions. The second is the "permanence effect" -- a stubborn tendency to stick with your beliefs and not change your mind, even in the face of contradictory evidence. Both of these effects result from your brain trying to avoid feelings of uncertainty.

If you have a high need for closure, research suggests you should be careful making decisions, especially in times of fatigue or stress.

"So, for example, let’s say you’re hiring someone, and you’re having a bad day or you’re on a deadline. Experiments have shown that you’re much more likely to focus on information early in the interview – for example, the first three minutes. And then you’re more likely to ignore contradictory information later in the interview," says Holmes.

Another common issue with a high need for closure is a proclivity to stereotype. Those who have a higher drive to resolve uncertainty may be quicker to ignore individual traits in favor of existing expectations.

The tendency can affect politics as well. For example, Holmes says, just reminding people of 9-11 makes them less willing to tolerate feelings of uncertainty. One study showed that American approval of George Bush's management of the economy rose or fell in tandem with the Department of Homeland Security's color-coded threat warning. Another study suggested that supporters of Donald Trump had one thing in common -- a preference clarity over ambiguity.

There are also links between a very high need for closure and political extremism, both on the right and the left of the political spectrum. One of the things that people who are drawn toward extreme ideology have in common is little tolerance for ambiguity.

The study of ambiguity intolerance actually arose after World War II, when Else Frenkel-Brunswik and Theodor Adorno created something called the “F scale,” which measured fascist tendencies. Decades later, Arie Kruglanski, a psychologist, spent time studying extremists in Northern Ireland, Palestine, Sri Lanka and elsewhere. He found that they all shared a very high need for closure.

"If you think about what characterizes extremism, it’s extreme certainty and complete inflexibility in the face of counter evidence," says Holmes.

While the need for closure is to some extent ingrained, people can deliberately lower it. Writing down pros and cons and being careful to make reasoned, deliberate decisions helps.

Two other surprising things that have been shown to lower our need for closure are reading fiction -- which invites us into the minds of other people -- and thinking about multicultural experiences, says Holmes. Likewise, studies show that just remembering time spent abroad, or a unique musical or culinary experience, can also lower a person's need for closure. The same kind of intervention made people less likely to stereotype and make discriminatory hiring decisions.

The upside of uncertainty

While many people think of confusion as a negative thing, Holmes says the reality is more nuanced. He calls uncertainty an "emotional amplifier," echoing the work of psychologists Tim Wilson and Daniel Gilbert.

Wilson and Gilbert carried out experiments in which they had subjects watch pleasant or unpleasant films, and then had them repeat phrases connoting certainty or uncertainty to induce certain emotions. It turned out that when subjects felt uncertainty, they took more pleasure in the enjoyable film, but also found the unpleasant film more unpleasant.

The result has also been shown for gifts. Studies show people derive more pleasure from being unsure whether they are going to receive one or two gifts than from knowing for sure they will receive two.

"So uncertainty amplifies the emotions of whatever you’re thinking about. It’s unpleasant to be uncertain about whether you’re going to be fired, but it’s pleasant to be at the Museum of Modern Art," says Holmes.

Indeed, looking at modern art, reading fiction, doing puzzles, eating new food, learning a new language, and traveling abroad all appear to make people more open to uncertainty, and more creative.

In a study last year, for example a researcher at the Columbia Business School reviewed 11 years of data on fashion brands. He found that the creativity of the fashion line increased the time top executives had spent traveling abroad.

There are other advantages to getting comfortable with ambiguity. Holmes argues that the ability to confront uncertainty is becoming more important for those who want to succeed in a changing economy.

Almost everyone agrees the U.S. needs more entrepreneurship and innovation. Yet one of the most important skills entrepreneurs need is the ability to confront problems that don't yet have answers, says Holmes. But this kind of problem has few parallels in classroom education.

For students, learning to deal with uncertain situations is not just an intellectual exercise -- it's an emotional one. Because uncertainty is an emotional amplifier, people who are innovating tend to experience very high highs and low lows. But with experience, people can learn not to get discouraged, and that wading through confusion is part of the creative process, Holmes says.

"Often times you have to push through confusion to get where you’re going."

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