Weak friendships and even encounters with people you don't know can affect your well-being, according to Karen Fingerman, professor of human development and family science at the University of Texas. She has studied interactions with what she calls "consequential strangers" and found that they can make or break a person's day and influence their mood. Think, for example, of the cheerful Starbucks barista you look forward to seeing on many days.
Casual acquaintances may also provide strong benefits. "The intimate ties give you a lot of emotional support," Fingerman says, "whereas your peripheral ties may help you with new information and diversions." Fingerman cites research showing that many of us find new jobs through our weaker social ties. "The people on the edge [of our social network] are the people who have access to information and to people that you do not know."
While social networks can be extensive, our core sets of close relationships are much smaller. "We found that the average American has just four close social contacts, with most having between two and six," Christakis and Fowler say in their research.
"People's social networks tend to shrink as they get older, especially as they get into middle age," Fischer says. This can increase loneliness and have an adverse affect on health. One antidote is to seek out new community groups and volunteer opportunities.
Developing relationships has been made easier by the emergence of Facebook and other widely used social media sites. "What social media does is that it brings us more into contact with weaker ties," Fowler says.
"The online stuff takes time away not from social ties, but from things like television and sleep," says Fischer. "There is no evidence that it undercuts face-to-face social ties."
Eli Finkel, an associate professor of social psychology at Northwestern University, researches the effect of online dating services on relationships. As many as 1 in 4 romantic relationships now start online, he says, compared with less than 1 percent that were triggered 20 years ago by personal ads in newspapers.
"You now have access to profiles of a large number of potential partners that you might be interested in," Finkel says, "and that's a godsend." But he feels online dating sites are misleading people when they say they've somehow "cracked the code" and can use technology to provide users with perfect matches. Neither the profiles nor the matching technology have yet replaced the value of face-to-face meetings and social interaction, Finkel says.
In the end, successful networks provide people with three strong types of benefits, Cohen says. One is social integration—being plugged into events, trends, and experiences beyond those that directly involve you.
Second, he says, is the social support provided to one another by network members. "When you care for other people, you're motivated to take better care of yourself," Cohen observes.
Lastly, social networks can insulate or buffer people from negative events. "Having people who you think will provide you with help when you need it helps protect you from the effects of stress on your health," Cohen says. Even when the protection is perceived, such as believing someone would "have your back" in a crisis, the benefit is real.