Contagious Why Things Catch On

public visibility.
If something is built to show, it’s built to grow.
THE PSYCHOLOGY OF IMITATION
Imagine you’re in an unfamiliar city. You’re out of town on a business trip or vacationing with a
friend and by the time you finally land, check into the hotel, and take a quick shower you’re famished.
It’s time for dinner.
You want to go somewhere good, but you don’t know the city that well. The concierge is busy and
you don’t want to spend a lot of time reading reviews on the Internet, so you decide to just find a
place nearby.
But when you step out onto the bustling street you’re struck by dozens of options. A cute Thai place
with a purple awning. A hip-looking tapas bar. An Italian bistro. How do you choose?
If you’re like most people you’d probably follow a time-tested rule of thumb: look for a restaurant
full of people. If lots of people are eating there, it’s probably good. If a place is empty, you should
probably keep on walking.
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.

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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.
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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.