Impact of social networks on behavior

[Steven Gordon]

I saw this article in today's Washington Post and thought that others  
might find it of interest.  It describes the power of social networks  
on individual behavior.

Steve

Social Networks' Sway May Be Underestimated
By Rob Stein
Washington Post Staff Writer
Monday, May 26, 2008; A06


Facebook, MySpace and other Web sites have unleashed a potent new  
phenomenon of social networking in cyberspace. But at the same time, a  
growing body of evidence is suggesting that traditional social  
networks play a surprisingly powerful and underrecognized role in  
influencing how people behave.

The latest research comes from Nicholas A. Christakis, a medical  
sociologist at the Harvard Medical School, and James H. Fowler, a  
political scientist at the University of California at San Diego. The  
pair reported last summer that obesity appeared to spread from one  
person to another through social networks, almost like a virus or a fad.

In a follow-up to that provocative research, the team has produced  
similar findings about another major health issue: smoking. In a study  
published last week in the New England Journal of Medicine, the team  
found that a person's decision to kick the habit is strongly affected  
by whether other people in their social network quit -- even people  
they do not know. And, surprisingly, entire networks of smokers appear  
to quit virtually simultaneously.

Taken together, these studies and others are fueling a growing  
recognition that many behaviors are swayed by social networks in ways  
that have not been fully understood. And it may be possible, the  
researchers say, to harness the power of these networks for many  
purposes, such as encouraging safe sex, getting more people to  
exercise or even fighting crime.

"What all these studies do is force us to start to kind of rethink our  
mental model of how we behave," said Duncan Watts, a Columbia  
University sociologist. "Public policy in general treats people as if  
they are sort of atomized individuals and puts policies in place to  
try to get them to stop smoking, eat right, start exercising or make  
better decisions about retirement, et cetera. What we see in this  
research is that we are missing a lot of what is happening if we think  
only that way."

For both of their studies, Christakis and Fowler took advantage of  
detailed records kept between 1971 and 2003 about 5,124 people who  
participated in the landmark Framingham Heart Study. Because many of  
the subjects had ties to the Boston suburb of Framingham, Mass., many  
of the participants were connected somehow -- through spouses,  
neighbors, friends, co-workers -- enabling the researchers to study a  
network that totaled 12,067 people.

When researchers analyzed the patterns of those who managed to quit  
smoking over the 32-year period, they found that the decision appeared  
to be highly influenced by whether someone close to them stopped. A  
person whose spouse quit was 67 percent more likely to kick the habit.  
If a friend gave it up, a person was 36 percent more likely to do so.  
If a sibling quit, the chances increased by 25 percent.

A co-worker had an influence -- 34 percent -- only if the smoker  
worked at a small firm. The effects were stronger among the more  
educated and among those who were casual or moderate smokers.  
Neighbors did not appear to influence each other, but friends did even  
if they lived far away.

"You appear to have to have a close relationship with the person for  
it to be influential," Fowler said.

But the influence of a single person quitting nevertheless appeared to  
cascade through three degrees of separation, boosting the chance of  
quitting by nearly a third for people two degrees removed from one  
another.

"It could be your co-worker's spouse's friend or your brother's  
spouse's co-worker or a friend of a friend of a friend. The point is,  
your behavior depends on people you don't even know," Christakis said.  
"Your actions are partially affected by the actions of people who are  
beyond your social horizon" -- but in the broader network.

In addition, the researchers found that the size of smokers' own  
networks did not change over time, even though the overall number of  
smokers plummeted, from 45 percent to 21 percent of the population  
during that time. The researchers realized that what happened was that  
entire networks of smokers would quit almost simultaneously.

"People quit in droves -- whole groups of people quit together at  
roughly the same time," Christakis said. "You can see it ripple  
through a network. It's sort of like an ant colony or a flock of  
birds. A single bird doesn't decide to turn to the right or the left;  
the whole flock has mind of its own."

The study did not examine why this occurs, but it is probably the  
result of a shift in social norms within each group -- smoking  
becoming unattractive or disparaged.

"Something changes in the zeitgeist that makes smoking unacceptable,  
and all these people move together in lockstep," Christakis said.

Another intriguing -- and disturbing -- finding was that as more  
people quit, the remaining smokers tended to wind up on the edges of  
society, with fewer and fewer social connections.

"In 1971, you have this crowd of people, and smokers are dispersed  
among them. But eventually by 2003, the smokers have been pushed to  
the periphery of the crowd," Christakis said.

That indicates that the remaining hard-core smokers are more socially  
isolated, which by itself has been shown by other research to have  
negative health consequences.

"So at the same time we are trying to help smokers to quit, we have  
unintentionally been hurting them by wreaking havoc on their social  
lives," Fowler said. "One of the implications is it's harder to reach  
smokers. Increasingly, they are huddled together in groups that are  
not connected to other people who don't smoke."

The findings could also have implications for the obesity epidemic.

"If we use these norms to fight the obesity epidemic, we may, in the  
process of stigmatizing the state of being overweight, further  
stigmatize obese people," Fowler said. "Smoking is an example of how  
we can create problems at the same time we solve others."
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