Contagious: Why Things Catch On (16 page)

This is just one example of a much broader phenomenon. People often imitate those around them. They dress in the same styles as their friends,
pick entrées preferred by other diners, and reuse hotel towels more when they think others are doing the same.
People are more likely to vote if their spouse votes, more likely to quit smoking if their friends quit, and more likely to get fat if their friends become obese. Whether making trivial choices like
what brand of coffee to buy or important decisions like paying their taxes, people tend to conform to what others are doing. Television shows use canned laugh tracks for this reason:
people are more likely to laugh when they hear others laughing.

People imitate, in part, because others’ choices provide information. Many decisions we make on a daily basis are like choosing a restaurant in a foreign city, albeit with a little more information. Which one is the salad fork again? What’s a good book to take on vacation? We don’t know the right answer, and even if we have some sense of what to do, we’re not entirely sure.

So to help resolve our uncertainty, we often look to what other people are doing and follow that. We assume that if other people are doing something, it must be a good idea. They probably know something we don’t. If our tablemates seem to be using the smaller fork to pick at the arugula, we do the same. If lots of people seem to be reading that new John Grisham thriller, we buy it for our upcoming vacation.

Psychologists call this idea “
social proof.” This is why baristas
and bartenders seed the tip jar at the beginning of their shift by dropping in a handful of ones and maybe a five. If the tip jar is empty, their customers may assume that other people aren’t really tipping and decide not to tip much themselves either. But if the tip jar is already brimming with money, they assume that everyone must be tipping, and thus they should tip as well.

Social proof even plays a role in matters of life and death.

Imagine one of your kidneys fails. Your body relies on this organ to filter the toxins and waste products from your blood, but when it stops working, your whole body suffers. Sodium builds up, your bones weaken, and you’re at risk of developing anemia or heart disease. If not treated quickly, you will die.

More than 40,000 people in the United States come down with end-stage renal disease every year. Their kidneys fail for one reason or another and they have two options: either go through time-consuming back-and-forth visits to a treatment center three times a week for five-hour dialysis treatments, or get a kidney transplant.

But there are not enough kidneys available for transplant. Currently more than 100,000 patients are on the wait list; more than 4,000 new patients are added each month. Not surprisingly, people on the wait list for a kidney are eager to get one.

Imagine you are on that list. It is managed on a first-come, first-served basis, and available kidneys are offered first to people at the top of the list, who usually have been waiting the longest. You yourself have been waiting for months for an available kidney. You’re fairly low on the list, but finally one day you’re offered a potential match. You’d take it, right?

Clearly, people who need a kidney to save their lives should take one when offered. But surprisingly, 97.1 percent of kidney offers are refused.

Now, many of those refusals are based on the kidney not being a good match. In this respect, getting an organ transplant is a bit like getting your car repaired. You can’t put a Honda carburetor in a BMW. Same with a kidney. If the tissue or blood type doesn’t match yours, the organ won’t work.

But
when she looked at hundreds of kidney donations, MIT professor Juanjuan Zhang found that social proof also leads people to turn down available kidneys. Say you are the one hundredth person on the list. A kidney would have first been offered to the first person on the list, then the second, and so on. So to finally reach you, it must have been turned down by ninety-nine other people. This is where social proof comes into play. If so many others have refused this kidney, people assume it must not be very good. They infer it is low quality and are more likely to turn it down. In fact, such inferences lead one in every ten people who refuse a kidney to do so in error. Thousands of patients turn down kidneys they should have accepted. Even though people can’t communicate directly with others on the list, they make their decisions based on others’ behavior.

—————

Similar phenomena play out all the time.

In New York City, Halal Chicken and Gyro offers delicious platters of chicken and lamb, lightly seasoned rice, and pita bread.
New York
magazine ranked it as one of the top twenty food carts in the city, and people wait up to an hour to get one of Halal’s tasty but inexpensive meals. Go during certain times of day and the line will stretch all the way down the block.

Now I know what you are thinking. People must wait that long because the food is really good. And you’re partially right: the food is quite good.

But the same owners operate an almost identical food cart called Halal Guys right across the street. Same food, same packaging, basically an identical product. But there is no line. In fact, Halal Guys has never developed the same devout following as its sibling. Why?

Social proof. People assume that the longer the line, the better the food must be.

This herd mentality even affects the type of careers people consider. Every year I ask my second-year MBA students to do a short exercise. Half the students are asked what they thought they wanted to do with their life right when they started the MBA program. The other half are asked what they want to do
now.
Neither group gets to see the question the other was asked and responses are anonymous.

The results are striking. Before they start the MBA program, students have a broad range of ambitions. One wanted to reform the health care system, another wanted to build a new travel website, and a third wanted to get involved in the entertainment industry. Someone wanted to run for political office and another student thought about becoming an entrepreneur. A handful say they want to go into investment banking or consulting. Overall, they possess a diverse set of interests, goals, and careers paths.

The responses from students when asked what they want to do a year into the program are much more homogeneous and concentrated. More than two-thirds say they want to get into investment banking or consulting, with a small sprinkling of other careers.

The convergence is remarkable. Sure, people may learn about different opportunities during the MBA program, but part of this herding is driven by social influence. People aren’t sure what career to choose, so they look to others. And it snowballs.
While less than 20 percent of people might have been interested in investment banking and consulting going into the program, that number is larger than any other career. A few people see that 20 percent and switch. A few more see those people switch, and they follow along. Soon the number is 30 percent. Which makes other people even more likely to switch. Soon that 20 percent has become much larger. So through social influence this initially small advantage gets magnified. Social interaction led students who originally preferred different paths to go in the same direction.

Social influence has a big effect on behavior, but to understand how to use it to help products and ideas catch on, we need to understand when its effects are strongest. And that brings us to Koreen Johannessen.

THE POWER OF OBSERVABILITY

Koreen Johannessen started at the University of Arizona as a clinical social worker. Originally, she was hired by the mental health group to help students deal with problems like depression and drug abuse. But after years of treating students, Johannessen realized that she was working on the wrong end of the problem. Sure, she could try to fix the ongoing issues that afflicted students, but it would be much better to prevent them before they started. So Johannessen moved over to the campus health group and took over health education, eventually becoming the director of health promotion and preventive services.

As at most universities in the United States, one of the biggest issues at Arizona was alcohol abuse. More than three-quarters of American
college students under the legal drinking age report drinking alcohol. But the bigger concern was the
quantity
that
students consume. Forty-four percent of students binge-drink, and more than 1,800 U.S. college students die every year from alcohol-related injuries. Another 600,000 are injured while under the influence of alcohol. It’s a huge issue.

Johannessen addressed the problem head-on. She papered the campus with flyers detailing the negative consequences of bingeing. She placed ads in the school paper with information about how alcohol affects cognitive functioning and performance in school. She even set up a coffin at the student center with statistics about the number of alcohol-related deaths. But none of these initiatives seemed to put much of a dent in the problem. Simply educating students about the risks of alcohol didn’t seem to be enough.

So Johannessen tried asking the students
how they felt about drinking.

Surprisingly, she found that most students said they were not comfortable with the drinking habits of their peers. Sure, they might enjoy a casual drink once in a while, just like most adults. But they weren’t into the heavy binge drinking they saw among other students. They spoke distastefully about the times they nursed a hungover roommate or held someone’s hair while she threw up in the toilet. So while their peers seemed fine with the drinking culture, they weren’t.

Johannessen was pleased. The fact that most students were against binge drinking seemed to bode well for eliminating the drinking problem—until she thought about it closely.

If most students were uncomfortable with the drinking culture, then why was it happening in the first place? Why were students drinking so much if they don’t actually like it?

Because behavior is public and thoughts are private.

Put yourself in a college student’s situation. When you look
around, you’d
see
a lot of drinking. You’d see tailgates at the football games, keg parties at the frat house, and open bars at the sorority formal. You’d witness your peers drinking and seeming happy about it, so you’d assume that
you
are the outlier and that everyone else likes drinking more than you do. So you’d have another drink.

But what students don’t realize is that
everyone
is having similar thoughts. Their peers are having the same experience. They see others drinking, so they drink, too. And the cycle continues because people can’t read one another’s thoughts. If they could, they’d realize that everyone felt the same way. And they wouldn’t feel all this social proof compelling them to drink as much.

For a more familiar example, think about the last time you sat through a bewildering PowerPoint presentation. Something about equity diversification or supply chain reorganization. At the end of the talk, the speaker probably asked the audience if anyone had any questions.

The response?

Silence.

But not because everyone else understood the presentation. The others were probably just as bewildered as you were. But while they would have liked to raise their hands, they didn’t because each one is worried that he or she is the only person who didn’t understand. Why? Because no one else was asking questions. No one saw any public signal that others were confused so everyone keeps his doubts to him- or herself. Because behavior is public and thoughts are private.

—————

The famous phrase “Monkey see, monkey do” captures more than just the human penchant for imitation. People can imitate
only when they can
see
what others are doing. College students may personally be against binge drinking, but they binge because that is what they observe others doing.
A restaurant might be extremely popular, but if it’s hard to see inside (e.g., the front windows are frosted), there is no way passersby can use that information to inform their own choices.

Observability has a huge impact on whether products and ideas catch on. Say a clothing company introduces a new shirt style. If you see someone wearing it and decide you like it, you can go buy the same shirt, or something similar. But this is much less likely to happen with socks.

Why?

Because shirts are public and socks are private. They’re harder to see.

The same goes for toothpaste versus cars. You probably don’t know what kind of toothpaste your neighbors use. It’s hidden inside their house, inside their bathroom, inside a cabinet. You’re more likely to know what car they drive. And because car preferences are easier to observe, it’s much more likely that your neighbors’ purchase behavior can influence yours.

My colleagues Blake McShane, Eric Bradlow, and I tested this idea using data on
1.5 million car sales. Would a neighbor buying a new car be enough to get you to buy a new one?

Sure enough, we found a pretty impressive effect. People who lived in, say, Denver, were more likely to buy a new car if other Denverites had bought new cars recently. And the effect was pretty big. Approximately one out of every eight cars sold was because of social influence.

Even more impressive was the role of observability in these effects. Cities vary in how easy it is to see what other people are driving. People in Los Angeles tend to commute by car, so they
are more likely to see what others are driving than New Yorkers, who commute by subway. In sunny places like Miami, you can more easily see what the person next to you is driving than in rainy cities like Seattle. By affecting observability, these conditions also determined the effect of social influence on auto purchases. People were more influenced by others’ purchases in places like Los Angeles and Miami, where it is easier to see what others were driving. Social influence was stronger when behavior was more observable.

Observable things are also more likely to be discussed. Ever walked into someone’s office or home and inquired about a weird paperweight on the desk or a colorful art print on the living room wall? Imagine if those items were locked in a safe or tucked away in the basement. Would they get talked about as much? Probably not. Public visibility boosts word of mouth.
The easier something is to see, the more people talk about it.