"The Digital Divide" has vexed and worried researchers for at least a decade, raising concerns that entire groups of Americans might be left behind, unable to afford the gadgets of the 21st Century.
Perhaps it's the social network divide they should worry about instead.
There is plenty of empirical evidence that those who choose to avoid Facebook, MySpace, and Twitter suffer social consequences: Ask anyone who missed a party -- or for that matter, a wedding -- that was organized on Facebook.
New evidence from a survey conducted exclusively for msnbc.com suggests that divide is becoming a pitched battle, with simmering frustrations between pro- and anti-social network crowds over an issue that is central to the digital age and the future of social networks: Privacy.
The survey suggests that Americans' opinions on privacy are polarizing towards two extremes -- it's become either much more important or much less important -- and the fault line is social media participation. It was conducted by The Ponemon Institute as part of msnbc.com's recent four-part privacy series.
The series comes as Congress and the Federal Trade Commission weigh a series of legislative initiatives designed to deal with online privacy issues, including the so-called Do Not Track list, modeled after the wildly popular Do Not Call list. The Senate Commerce Committee is scheduled to hold a hearing on the issue on Wednesday.
Avid Facebook users said they care much less about privacy than they did five years ago, falling deeper into the "I have nothing to hide, so why worry" category; social media avoiders said they care much more now, and are more concerned than ever about their ability "to be left alone."
(For a deeper exploration of these points of view, read Wilson Rothman's piece aimed at the nothing to hide crowd, Helen Popkin's piece for the privacy elite, and my piece for the middle-of-the-road audience.)
Ordinarily, when asked a more/about the same/less question, most survey takers opt for the middle choice, said Larry Ponemon of The Ponemon Institute. In this case, 36 percent said they cared less about privacy than five years ago, and the same percentage said they care more. Only one in four picked "about the same."
"It is a surprising result," he said. "The fact that the numbers are pulling to each side is an interesting finding. The fact is there's not a lot of complacency about privacy now. People are thinking about this."
A look inside the numbers offers an easy explanation for the polarization: Among active social network users, 58 percent said privacy was less important and only 14 percent said its importance was growing. Non-social media users were almost a mirror image in reverse, with 53 percent saying privacy is more important to them, but only 20 percent saying it was less so.
Privacy has been a vexing topic for researchers because consumers for years have said it's important to them, but rarely act out of that concern. They won't often shun supermarket discount loyalty cards, for example. Any survey result in which consumers admit caring less about privacy is intriguing, Ponemon said.
"It's the old convenience argument. I want a reason to do the things I like to do," he said. People who have chosen to use Facebook and its rivals want to believe they are safe; and very few people have experienced any real trouble from their privacy choices. "People's experience seems to be, 'I went in the water and the shark didn't eat me, so they continue doing what they like to do."
On the other hand, the mere existence of social media tools has pushed non-users to think more seriously about privacy, Ponemon said.
Who doesn't use social networks? You'd be surprised. According to the Pew Internet and American Life Project, 39 percent of U.S. adult Internet users still aren't on Facebook, Twitter or a similar service. Non-users tend to be male (44 percent to 33 percent for women), older (56 percent of 50- to 64-year-olds aren't users), have less education (45 percent of non-high school graduates aren't) and less income (40 percent of those earning less than $30,000 aren't), according to Pew.
Privacy concerns are one of myriad reasons why someone might not join a social network.
Of course, you don't have to be a member of a social network to have your privacy violated by the service. Non-Facebook users, for example, can have their photograph taken, published and shared a million times over on the site.
Alessandro Acquisti, an economist who studies privacy at Carnegie-Mellon University, says the privacy issue may be polarizing because the penalty for avoiding social networks is becoming more severe over time.
"Not having a mobile phone now would dramatically cut you off from professional and personal life opportunities. It's the same story with social networks," Acquisti said. "The more people use them for socializing and for their professional life, the more costly it becomes for others (who aren't members) to be loyal to their views."
The cost in some ways is basic. Many Facebook users now assume all their posts are common knowledge, and skip old-fashioned ways of communicating even important events now. That leads to awkward, "What do you mean you didn't know I was engaged" conversations.
For some, the consequences are far more serious. It's hard to imagine a more powerful tool for job-search networking that Facebook; it's easy to imagine an unemployed worker suffering for taking a stand against joining the service. This social media usage gap effect could ultimately be as dramatic, or even more so, than the digital divide.
"I don't presume to have a good answer," Acquisti said. "But one can make an argument that protecting privacy in a world where people don't see the value of it is going to become costlier and costlier. That means some people's right to privacy is being rendered more difficult to protect precisely by the right of other people not to care about privacy."
Behind the numbers
The Ponemon Institute survey estimates that 42 percent of U.S. adults call themselves "active users" of social networks.
One interesting finding of the research: While Congress and companies involved extol the virtues of giving "control" of personal data to consumers as a solution to troubling privacy issues, users themselves are under no illusions that they maintain control. By equal amounts, both social network users and non-users overwhelmingly say they have less control over their data today than five years ago -- about 70 percent say they have less control; 18 percent say they about the same control; and only 1 in 7 users say they have more control.
Meanwhile, virtually no one believed the statement: "I am confident that I can protect my personal information when I'm online." Only 4 percent “strongly agreed”; another 14 percent agreed, while 33 percent disagreed and 18 percent strongly disagreed. The results, again, were essentially the same for social media users and non-users.
One in two users said they'd suffered a privacy-violating experience in the past two years, with most of them saying they'd been hit several times. Two-thirds said they'd suffered between four and 10 privacy violations during that time. The results were the same for social media users and non-users.
One in four survey takers said they'd been a victim of identity theft during their lifetime.
Consumers said they trusted the government more than private corporations by a factor of 2.5-1 when it came to protecting privacy, but two-thirds of respondents said they trusted neither.
The Ponemon survey was conducted using an online panel that included a representative sample of U.S. adults and comes with a margin of error of +/- 4.5 percent.