MR. KOJO NNAMDIFrom WAMU 88.5, at American University in Washington, welcome to "The Kojo Nnamdi Show," connecting your neighborhood with the world. It's Tech Tuesday. Social media technologies and social unrest seem to go together like peanut butter and jelly. You can't read news stories about democratic uprisings anymore without passing by phrases like Facebook revolution and Twitter generation.

MR. KOJO NNAMDIBut for as much as social media have been given credit for launching demonstrations in the so-called Arab Spring, these tools are also taking the blame for contributing to the chaos of the riots that consumed London and for violent flash mobs in American cities. Britain's prime minister recently suggested banning certain social media platforms, blaming them for fanning the flames of unrest.

MR. KOJO NNAMDIAnd public transit police in San Francisco and the San Francisco Bay Area recently cut off cell phone service to thwart protesters from organizing there this past week. Joining us to explore the roles and responsibilities of the tech companies themselves and where they fit in to broader conversations about free speech and human rights is Cynthia Wong.

MR. KOJO NNAMDIShe is the director of the Project on Internet Freedom at the Center for Democracy and Technology, CDT. Cynthia Wong, thank you for joining us.

MS. CYNTHIA WONGThanks for having me.

NNAMDIJoining us by telephone is Jennifer Preston. Jennifer Preston is a reporter for The New York Times. Jennifer Preston, thank you for joining us.

MS. JENNIFER PRESTONThank you for having me.

NNAMDISocial media have played starring roles this year in stories around the globe about people trying to exercise free speech, organize protests, challenge regimes. It's become trite to call events from the Arab Spring, for example, part of the Facebook revolution. But, lately, social media have started to take the blame for everything, from riots in Britain to flash mobs here in the States.

NNAMDIAnd government officials are starting to act on it. What do you make of the recent pushback on social media, particularly from Western democracies, like Britain, Cynthia Wong?

WONGSure. I mean, at first, I think we need to fully acknowledge the seriousness of the violence and the damage that was done during the riots in London. Those responsible for the harm there really should be brought to account and be pursued. And, certainly, law enforcement does have legitimate needs when it comes to addressing this kind of violence, unrest and identifying wrongdoers.

WONGThat said, I think going down the route of shutting down social media tools in response to unrest or security threats is an extremely slippery slope. And I think taking this path has troubling implications for human rights, both within countries like the U.K. and the U.S. and outside. I know in the heat of the moment, there was a lot of focus on the use of BlackBerry Messenger, which is a private communications tool that people with BlackBerry devices can use.

WONGAnd the prime minister, at the time, talked about blocking BlackBerry messaging services. But I think that, if you really think about it, it's really doubtful that blocking one social media service would really deter rioters who are intent on committing violence. You know, rioters could then turn to a variety of other social media tools that also enable mass communication.

NNAMDIWell, let's talk about social media tools in general because the aforementioned prime minister, David Cameron, said last week that, quoting here, "the free flow of information can be used for good and used for ill." How did you react about -- upon hearing that?

WONGI mean, I think that is absolutely true, and that's really where the problem comes in. When you start blocking these kinds of general purpose communications tools, you're also impacting the rights of completely innocent citizens. And, in fact, in the London case, there was evidence that citizens were actually using the same social media tools that rioters were using to organize cleanup efforts and to even warn their neighbors if the violence was headed their way.

NNAMDIA point we were going to get to later. If you'd like to join this Tech Tuesday conversation on social media and social unrest, you can join it on Twitter. Just go to the Tech Tuesday hashtag, or you can call us at 800-433-8850. Send email to kojo@wamu.org, or you can go to our website, kojoshow.org. Ask a question or make a comment there.

NNAMDIJennifer Preston, would you consider text messaging or instant messaging to be social media? How do you feel about the fact that politicians seem to put them in the same category?

PRESTONWell, I think that's one of the big challenges here. Social media, many people would say, does not include BlackBerry Messenger service. It's a private communications tool. So one of the mistakes, I think, elected officials are making when they talk about placing restrictions on social media is that they're confusing the technology here.

PRESTONBlackBerry Messenger is a private communications tool. And that is, you know, what many people say has been used, or was used, during the London riots. And it's really unclear, still, what role Facebook and Twitter, two social media platforms, had in organizing the riots.

NNAMDIJennifer, earlier this year, former Egyptian President Hosni Mubarak tried to quash dissent basically by shutting down the entire network inside his country. But you also wrote about how Syria's government tried to zero in on social networks, like Facebook, and video sharing sites, like YouTube, just a few months after they had allowed citizens to use them in the first place. What did you learn by following this story in Syria?

PRESTONWell, what I learned in Syria was, in early February, the Syrian government changed its policy and allowed users in -- people in Syria to sign up for Facebook. At the time, many human rights activists warned that the government was changing its policy here, so that it could more closely monitor activities of its people.

PRESTONAnd that proved to be true, just a couple of months later, when many Syrians found themselves being summoned to police headquarters and ordered to turn over their Facebook pages and their Facebook passwords, which allowed authorities to identify people involved in the uprising there. So while I think that we have seen social media tools help fuel pro-democracy movements in Tunisia, in Egypt, social media tools can also be a -- can also create some very serious dangers for activists, as we've seen in Syria.

NNAMDIIf you'd like to join the conversation, how do you feel social media, like Facebook and Twitter, have contributed to unrest, like the riots in Britain or flash mobs in the United States? Again, you can call us at 800-433-8850. Or keep up with the conversation on Twitter by using the Tech Tuesday hashtag. Let us know what you're thinking on Twitter. Just use that Tech Tuesday hashtag.

NNAMDICynthia Wong, when you pick apart what David Cameron said last week, what can you say is different about what he seemed to be advocating, that what some of the authoritarian regimes, such as Hosni Mubarak's in Egypt, already did?

WONGWell, I think I want to be very clear that I would never try to equate the prime minister and his government and the Mubarak regime. I think that in the U.K., as well as in the U.S., citizens, obviously, have mechanisms to hold their public officials accountable and to help prevent abuses of power that can be exercised over social media and communications tools.

WONGI think what the difference here is that what the U.K. does in terms of the way that it responds to social unrest, if it responds in a way that undermines the rule of law, that undermines human rights, it actually sets a really bad precedent outside of the U.K. as well. It allows foreign governments, perhaps repressive governments, to point to the actions of these governments, Western democracies, who are disregarding human rights to justify their own practices.

WONGAnd, in fact, China has actually already done so. There's been a couple of editorials written in Chinese national newspapers that have essentially said, look, the democratic West is really rethinking their approach to human rights, to freedom of expression and looking at what this permissive approach has really engendered, the kind of violence its engendered, and so that maybe we should do so as well.

NNAMDIWell, government pushes for blackouts and crackdowns put another group of people in a rather awkward position. And that is the tech companies themselves, don't they?

WONGYes. Absolutely. And, I think, one of the kind of curious things about freedom of expression and human rights in the digital age is that so many of the ways in which we communicate, the ways in which we live our lives are actually done, mediated through these online tools that are owned and operated by private companies.

WONGAnd so when governments approach these companies to ask for their help in censorship or surveillance or in other actions that could harm human rights, it raises real questions as to how those companies should respond.

NNAMDIBecause, on the one hand, those companies want to keep doing business in those countries. On the other hand, it is not, I guess, their business to, I guess, censor speech.

WONGWell, that's one way of putting it. And I think that there's a growing social expectation among kind of progressive Western democracies and also of users, that companies do have a responsibility to respect the human rights of their users when they're approached by governments to take problematic action.

WONGAnd what does this really mean in practice? And I think that what companies should be thinking about is, what are the human rights risks that are raised by my business practices? How am I going to respond to governments when they do ask me to help censor and surveil? (sic) And what are the steps I can take to help mitigate those human rights risks?

WONGBecause no company, from either a public relations perspective or from a business perspective, wants to be viewed as complicit in the human rights violations of government.

NNAMDIWell -- and I like the fact that you raised those questions. I'm not going to ask you to answer them...

NNAMDI...at least not yet. Let's go to the telephones first. Here's Allan in Arlington, Va. Allan, you're on the air. Go ahead, please.

ALLANThank you so much for taking my call. I wanted to talk a little bit about an issue that was raised earlier when you were talking about how people used social media for good purposes and for bad purposes. And it seems, to me, like a good practice, I mean, if you can use it with what -- use social media to whatever end you would like to, but that does not mean that you won't be prosecuted criminally. And I just wanted to hear your thoughts on that.

NNAMDIWell, I'm not sure I fully understand the question. You're saying that, regardless of the purpose for which you use social media, you can be prosecuted? I mean, if you...

ALLANOh, no. I'm sorry. So what I was saying is people use social media for a variety of reasons, whether they'd be to gather people to clean up after the riot or to coordinate places so that they can riot. And, I mean, as far as the government imposing restrictions on that, it just seems like the government -- I feel like they should step back.

ALLANI mean, they can take steps to maybe listen in using the Patriot Act or whatever. But as far as letting whatever the people using the social media and what they're planning play out, and, I mean, if they're planning to do something for evil, I mean, they can be prosecuted in a criminal court...

NNAMDIYeah, but the question, I guess, that has to be raised is, if the government finds out that people are using social media to plan what would essentially be a crime, do they wait until after the crime was committed before they prosecute? Or do they something to stop it? But I'll take your question in two parts. I'll deal with the first part, first, and that is for people who are using it to, as you say, do good.

NNAMDIJennifer, you wrote about how some Londoners were using social media to help organize cleanup efforts after the nights of riots and looting last week. How so?

PRESTONWell, a group of people on Twitter wanted to do something to help and support the people and the neighborhoods where the riots took place. And so they took to Twitter to organize what was called riot cleanup. And what they did was they identified people in different neighborhoods to meet folks as they came off the subway, armed with brooms and dustpans and gloves, to help clean up the mess.

PRESTONSo, I think, that's an example of how social media was used in a positive way during the U.K. riots. And also, to answer Allan's question regarding law enforcement, law enforcement authorities in the U.K. used social media, used Flickr. They used YouTube to help identify looters and people involved in the riots.

PRESTONAnd what also happened, which was very interesting -- and the same thing happened in Vancouver -- is people created blogs and took to platforms to help law enforcement identify looters. There was a Tumblr blog, where people posted photographs and information to help law enforcement, you know, identify people responsible for the violence and for the damage during the riots.

PRESTONSo, I think, that's an example of how social media can be used in a positive way during periods of unrest.

NNAMDIAllan, thank you very much for your call. On the other hand, Cynthia Wong, some people have assigned blame to social media for helping organize flash mobs that have gotten out of control here in the United States. Public transit officials in San Francisco went so far as to shut down underground cell phone services this weekend to thwart a protest people were planning there.

NNAMDIWhat do you make of what's been happening in California? And what do you think authorities need to do, period, about social media being used to organize criminal activity?

WONGSure. And I think I would want to push back a little bit about overstating the role of social media in inciting riots or inciting people to unlawful activity.

PRESTONYeah, I agree with Cynthia there. I think it's been overstated.

WONGYeah, especially in the -- if you look at the London context, you know, a lot of the trouble seemed to have started in a very localized ways, right? So it's street gangs or people who have come from the same neighborhood who have similar grievances or similar kinds of inclinations towards, you know, illegal behavior.

WONGAnd even if social media were, in part, used to organize rioters or point them to the right place, I think the fact that these existing social networks -- offline social networks already existed -- really speaks the fact that these things may have happened anyways even if BlackBerry Messenger were shut down or if Twitter were shut down, et cetera. And, frankly, I think that, also, the riots were made worse because people were watching what was going on on TV.

WONGAnd they saw, oh, people are getting free tennis shoes or televisions or iPads, and I want that as well. And so I would be very careful in overstating the role that social media plays in order to justify kind of these broad governmental powers to shut down social media, which has many other negative effects.

NNAMDIJennifer Preston, you feel that the role of social media in the riots in Britain, and maybe in flash mobs here, is exaggerated?

PRESTONYes. And, again, I go back to what I said earlier. I think that we have to distinguish between BlackBerry Messenger service, IMs and text messages on a private communications network, that we have to draw a distinction between that technology, you know, that communications tool and social media platforms, like Twitter and Facebook. But, at the same time, there are very serious questions, you know, raised.

PRESTONWe now have the FCC investigating BART's decision over shutting down cell phone service. And that decision, you know, prompted protests yesterday. So, I think, what a lot of government officials and law enforcement officials are struggling with right now is the pace of change. It's coming so quickly that we are going to run into a lot of bumps along the road as people try to strike the balance that Cynthia has discussed, about human rights and civil rights and civil unrest.

NNAMDIJennifer Preston is a reporter for The New York Times. She joins us by telephone in this Tech Tuesday conversation on social media and social unrest. Joining us in studio is Cynthia Wong, director of the Project on Internet Freedom at the Center for Democracy and Technology. If you'd like to join the conversation, you can call us at 800-433-8850. Or simply go to Twitter and use the Tech Tuesday hashtag.

NNAMDIHow do you feel social media, like Facebook and Twitter, have contributed to unrest, like the riots in Britain or flash mobs in the United States? What information do you willingly give up to the social media that you use? Do you have concerns that your offline and online worlds are converging? And where do you think social media should fit into the effective policing strategies?

NNAMDIWe go to Brad on the telephone in Washington, D.C. Brad, you're on the air. Go ahead, please.

BRADHi. Thank you for taking my call. I guess my question is really focused on David Cameron's comments about this private messaging system. And could it have better been -- couldn't he have better been served had he made a maybe offline request to the company -- is it RIM? -- that runs the system and said, look, would you, please, collaborate and cooperate with our police to ensure the safety or, you know, mitigate, you know, violence and so on and so forth and limit access at this point?

BRADBecause it is a private thing and it is sort of -- you know, you can make the appeal, I would think, to the company, you know, for the -- as a good citizen. It's a little bit different -- and that's different from this virtual, digital town green, in which conversations happen, which is Facebook and Twitter and things like that.

BRADSo I think that there is a definite distinction between a company-run, corporate, you know, space versus a virtual town green. And could he have better been served? So I'll take my -- listen to you guys on the air.

NNAMDICynthia Wong?

WONGSure. I mean, I think the reality is, is that nearly all governments will ask technology companies to help with user -- access to user data or to help with surveillance, especially when it comes to legitimate situations, like law enforcement investigation or dealing with unrest. And when I say all governments, I mean both democratic governments and the kind of repressive governments that we saw at issue earlier this year, like in Egypt and Tunisia.

WONGAnd the question, really, then becomes, what are the protections and what are the standards government must meet in order to force companies to help with surveillance and help with actions that actually hurt -- could hurt or could harm user privacy?

WONGAnd I would say, it's actually pretty important for governments to continue to follow their own processes and to kind of abide by their own protections that are in their own law because if they act in ways that undermine the rule of law or due process in response to unrest, it really does undermine freedom of expression, actually, outside of their borders. For example, RIM, it is an international company.

WONGThey operate all over the world, and they're actually being faced with a lot of government pressure in more problematic areas where the rule of law and human rights is weak. And if the U.K. government asks RIM to comply with a request that doesn't actually follow U.K. law and RIM agrees, then it makes it much more difficult for any company to say no to a government that may not be so concerned about human rights.

NNAMDIJennifer, what sense do you have for these companies? Some of these companies see themselves on the spectrum of free speech and human rights. You reported earlier this year that Facebook, for example, will remove pages that call for violence or advocate hate. So it seems that free speech on some of the social networks isn't exactly an absolute.

PRESTONWell, I think it's a big challenge for all of these companies. And I think Cynthia made some excellent points about the challenges, for example, facing RIM. With Facebook, during -- there was a Facebook page that was calling for a Palestinian uprising earlier this year. And Facebook was under a lot of pressure by groups around the world to take down that page.

PRESTONBut the page did not violate its terms of service until it was -- did not immediately violate the terms of service, but they did take the page down once the page concluded that people on the page, the admins on the page and people commenting on the page, were inciting violence. So all of these companies have terms of service that users need to be aware of when they use these platforms.

PRESTONAnd companies like Facebook will take down a page, will remove content if they believe that content is inciting violence or is inappropriate in some other way.

NNAMDIGot to take a short break. When we come back, we'll continue this conversation. Jennifer Preston, I know you have to go. Thank you so much for joining us.

PRESTONThank you.

NNAMDIJennifer Preston is a reporter for The New York Times. She joined us by telephone. The conversation on this Tech Tuesday is about social media and social unrest. Still in studio with us is Cynthia Wong, director of the Project on Internet Freedom at the Center for Democracy and Technology. We're still taking your calls at 800-433-8850.

NNAMDIHow have global events during this past year changed how you view the power and influence of social media? Do you look at Facebook or Twitter differently in the wake of the Arab Spring? You can join the conversation by using the Tech Tuesday hashtag. Let's know what you're thinking on Twitter. I'm Kojo Nnamdi.

NNAMDIIt's a Tech Tuesday conversation with Cynthia Wong, director of the Project on Internet Freedom at the Center for Democracy and Technology, CDT. We're talking social and media and social unrest, inviting your calls at 800-433-8850. Or you can simply join the conversation on Twitter by using the Tech Tuesday hashtag. Cynthia Wong, at least in the view of the courts, the limits of free speech here in the U.S. are pretty boundless.

NNAMDIThe Supreme Court recently protected speech at protests outside funerals for veterans, but from a philosophical standpoint, not a legal one. Where do you think the operators of this site should be willing to draw the line when it comes to situations like this? You've talked a little bit about this already.

WONGIn terms of operators of the social media websites?

NNAMDICorrect.

WONGWell, the -- I think Jennifer mentioned this earlier. But I think the reality is these social media sites, they all have their own rules and terms of use. And all of us as users are really bound by them. And so, I think, actually, that's what makes it so much more important to really examine how companies just want to -- especially governmental pressure that could impact our human rights.

WONGI think that one thing that companies could be doing is being more transparent about how they enforce their rules of the road, of their terms of use, and how they respond to governmental requests for user information that could impact all of our privacy rights. Because I think that users legitimately want to know what their privacy risks or what they're risk to their ability to speak is when they choose this social media platform versus another.

NNAMDIExactly how do you think social media platform should restrict speech when necessary? Call us at 800-433-8850. How has the arc of events throughout this year shaped your view about the power and influence of social media? Do you size up these companies differently now than you did, say, a year or so ago?

WONGI think the responsibilities of the companies remains the same, which is, look, anytime you're offering a communications tool that can be used by users to do good things and bad things, there will be times when government will try and step in and put pressure on you to restrict the rights of users as the kind of person in the middle.

WONGAnd I think the question then becomes, you know, how are you thinking about those risks? How are you working to mitigate the risk to your users? And what strategies do you have moving forward?

NNAMDIJoining us now by telephone is Alessandro Acquisti. Alessandro Acquisti is a professor at Carnegie Mellon University. Thank you so much for joining us.

PROF. ALESSANDRO ACQUISTIMy pleasure. Nice talking to you.

NNAMDIAlessandro, people willingly hand over tons and tons of personal data to social networks, everything from their favorite television shows to where they just checked into for lunch. But you recently conducted a study that found it's possible to successfully identify people in real life, even identify their Social Security information based on day-to-day hand-over to Facebook. What did you find?

ACQUISTIRight. This study was part of a stream of -- or a search we have been doing on not just what people are revealing online on social networks, but what those can be inferred about them due to progresses in what is called statistical identification, which is the beauty of combining data from different sources and come up with something where the ultimate piece of information may be much more sensitive than what you started from.

ACQUISTISo what we did in this particular instance was to combine data from online social networks and particular photos of people from Facebook, use off-the-shelf face recognizer, power -- computing power provided by cloud computing. And, indeed, the statistical identification techniques to see whether the combination of all these tools can make it possible to blend online, you know, flying data and end up predicting sensitive information starting from an anonymous face. And the answer is yes.

ACQUISTIWhat we did work is a proof of concept. But I have no doubt, considering the evolution on these technologies, that five to 10 years out of this will be not just a proof of concept, but will be applicable in a massive scale.

NNAMDIIt's my understanding that you even went so far as to create a mobile phone app that could do guesswork on a person's identity and personal information, just based on a photo.

ACQUISTIThat's correct. And we did develop a smartphone app. We have no intention, whatsoever, releasing it to the public. We developed it to make a point, to show that this future is already now. The phone application does the following: If it's a smartphone with a camera, you take a shot of a person. Take the shot. Upload it to a server.

ACQUISTIOn the server, there is an application, which, using face recognition, tries to compare the shot of the face you have just taken to a number of the faces coming from online social networks where people use not just their photos, but also their real names. If it does find a match, it tries to use that name to find for more information online about the name.

ACQUISTIAnd if it does find information, such as the person's date of birth and the hometown or, luckily, state of birth, then it uses an algorithm that I developed in 2009 in out of publish research to predict the person's Social Security number, and then sends back the Social Security number to the phone. And then the number and the name of the person appear so overlaid on the face of the person on the screen.

ACQUISTIAnd the point we are trying to make is that we are really, really close already into this future where this offline and online data can blend in almost real time.

NNAMDIThat's it. I'm taking down my Facebook photo and putting up the photo of somebody I really don't like onto my Facebook.

NNAMDIBut you can call us. What information do you willingly give to the social media that you use? Do you have concerns that your offline and online worlds are converging? Call us at 800-433-8850 or join the conversation on Twitter by using Tech Tuesday hashtag.

NNAMDICynthia, British police have confirmed that they're using facial recognition technologies to identify suspects in the riots we were talking about. But they've also posted photos online on the photo sharing site Flickr of people suspected of serious crimes. What do you make how photo sharing fits into this picture here and, potentially, facial recognition software?

WONGI think this raises serious challenges for activists, especially activists who live in closed societies and, therefore, have to rely on online media much more because traditional media is so much more closed off to them. We also saw this, I think, in the Iranian protest context as well, where the Iranian government posted pictures of demonstrations and asked people to help identify those people and were actually using Facebook to identify activist networks.

WONGAnd I think the real lesson to pull from this, especially from the corporate responsibility perspective, is that companies, even when they're trying to design a really cool new tool that teenagers in the U.S. and the U.K. can use, really need to think through and anticipate some of these uses, abuses and misuses of their very cool gadgets and think about what human rights risk might come up.

NNAMDIWould you agree with that, Alessandro?

ACQUISTII think it's a yes. I think it is a very good point. I -- what concerns me in -- about what is happening is that we tend to believe that these new technologies, such as online social networks, are giving weapons to both sides, the establishment and the anti-establishment, the power and the counter-power. But I'm not so sure there is such a balance.

ACQUISTII -- in fact, I see the risk of even more asymmetric power in a sense that uprisings and assembling and protesting long pre-date online social networks. We are social animals. We always find ways, regardless of the technology available to us, to organize, assemble a protest.

ACQUISTIOn the other hand, considering the state of online data retention loads and the fact that online social network providers want their members to create profiles with their real actual names, I wonder whether -- the matter of fact is that the users of online social network helps a little bit the effort to organize social movements, but helps a huge bit to the monitoring and surveillance of those efforts.

NNAMDIInteresting. Because here's what Brenda in Washington, D.C., has to say about what happened here. Brenda, that was what, back in 1995 or 1991, correct?

BRENDAYes. Well, my comment is, before cell phones and before BlackBerries, there has always been a network of so-called grapevines. Years ago, back in 1995, I was riding the bus and a young man commented, there is going to be a riot in Mount Pleasant. And I didn't believe him, but sure enough there was a riot.

NNAMDII'm sorry. I think it was 1991.

BRENDA'91?

NNAMDICorrect.

BRENDAOkay. Sure enough...

NNAMDIYeah.

BRENDA...it was -- there was a riot in 1991. So there's always been that network, and there will always be that network. Also, there is something called the professional protesters, and they go all over the country teaching people how to protest and use different tactics when protesting. And that started with the IMF, the International Monetary Fund protest.

NNAMDIWell, there have always been activists and organizers, people protesting what they see are unfair policies in some way or another. And, I guess, Cynthia Wong, social networks and social media simply give people, I guess, a little broader outreach. But as the point has been made already, people have always found ways in which to communicate and assemble.

WONGI think that's right. And, I think, just to build on something Alessandro said, I think what's different now than what has been true in the past is that many of our communications tools, especially our mobile phone, enable surveillance in a way that was just completely impossible before. We are all walking around with -- we are essentially points of data that can be tracked wherever we go when we carry our cell phones in our pockets.

WONGAnd, I think, especially to build on Alessandro's point, is that companies, again, needs to be thinking about what they might be asked to do by government when unrest actually happens, and what companies are going to do to help protect the rights of their users because they are in this kind of very difficult position where they are very much in a position to help.

NNAMDIGot to take another short break. When we come back, if you have already called, stay on the line. We will get to your call. If you have not called yet, we still have lines open, 800-433-8850. You can join the conversation on Twitter by using the Tech Tuesday hashtag. Where do you think social media should fit into effective policing strategies?

NNAMDIHow do you feel social media like Facebook and Twitter have contributed to unrest, like riots in Britain or flash mobs here in the United States? I'm Kojo Nnamdi.

NNAMDIIt's a Tech Tuesday conversation on social media and social unrest. How have global events during this past year changed how you view the power and influence of social media? Call us, 800-433-8850. Do you look at Facebook or Twitter differently after the Arab Spring? Join the conversation on Twitter using the Tech Tuesday hashtag.

NNAMDIJoining us in studio is Cynthia Wong, director of the Project on Internet Freedom at the Center for Democracy and Technology, CDT. Joining us by telephone is Alessandro Acquisti. Alessandro is a professor at Carnegie Mellon University. Alessandro, you said that part of what's fascinated you about this experiment is that it proves that online and offline data are converging into an augmented reality. What do you mean by that?

ACQUISTISo we use the term augmented reality in a slightly extended fashion. Technically, people started using the term to refer to applications, such as an iPhone app, where some information coming from the online world is overlaid on maybe images coming from the offline world. So you may be pointing your smartphone in a certain direction, to a lake or to a building, and on the screen you can see what is the name of the lake, what is the name of the building because online and offline data are blending.

ACQUISTIAnd we use this expression for our scenario, which is similar, and it relates to how you can take someone's anonymous face in the street, end up finding something personal, even sensitive about the person online. And then you can overlay that information on the person's face on the iPhone app or on the smartphone app.

ACQUISTIBut, by extension, we use it also to refer to this blending of online and offline data. Your face is the veritable conduit between your offline persona, who you are in the real world out there, and your online persona or personas because it's easy to create several online. It's much more difficult to change your face every time you go into a different scenario or different environment.

ACQUISTIAnd because the face is this conduit between your different personas, it creates this link between this offline and online world.

NNAMDIHere's Ben in Arlington, Va. Ben, your turn.

BENHey, Kojo, thanks for taking me. I have a question of the app that predicted the Social Security numbers. How exactly is that data created? I believe it was a prediction. And how accurate are these predictions? Is it 90 percent, 95 percent?

NNAMDIAlessandro?

ACQUISTISo the accuracy changes, depending on a number of factors. In the study, we published -- the results I presented last week for the Social Security numbers were based on a study we published in 2009. For the first five digits, we have very, very high accuracy, averaging across different states and different years of birth.

ACQUISTIWith two attempts, we could predict about 67 percent of all of Social Security numbers issued after 1989 with just two attempts, the first five digits of the SSN. For the last four, which change more rapidly, the issue becomes when and where you are borrowing because if you are borrowing in a large, very highly populated state, such as California, our prediction accuracy is no better than random chance.

ACQUISTIIf, instead, you're borrowing in a smaller state, especially in more recent years, after 1988, 1989, our accuracy can go up very, very quickly.

NNAMDIBen.

BENThanks so much.

NNAMDIBen, thank you very much for your call. Alessandro, how do you expect people would react if a mobile phone application, like the one you developed, ever made it to market?

ACQUISTII feel it's almost inevitable that we'll make it to market, not right now. The day when you can go in the street and recognize everyone's face (unintelligible) for the fresh information about them is not yet arrived for both computational reasons and reasons of accuracy of data. But it will come. The day will come.

ACQUISTIAnd, in a way, it's -- for me, it's both exciting and concerning to think about how we will react because we -- in the discussion of our results of the face recognition study, we talk about democratization of surveillance and in the sense that these technologies will make possible, not just for powerful government entities such as the NSA, but to anyone in the street to find out who the stranger passing by on the street is.

ACQUISTIAnd this democratization of surveillance is a double-edged sword, as it often comes -- when we talk about privacy, there is sometimes a way where privacy helps free speech. And there are other cases in which privacy is in conflict with free speech. So the world where anyone can recognize you in the street and find out your political, religious or sexual preferences, just by looking at your face, is a potential concern to me.

NNAMDICynthia Wong, is there any precedent for American police, law enforcement using photos taken from Flickr or a public Facebook album to identify a suspect or to stand as evidence against a suspect?

WONGYou know, I don't know of any specific incidents. But I do think that what Alessandro is saying and his research is suggesting is we need to ask whether we need new legal protections to address potential governmental uses of this kind of facial recognition technology. As Alessandro alluded to, the right to privacy is not absolute, and it can be restricted in certain circumstances, especially with -- when it comes to law enforcement investigation.

WONGBut then the question then becomes, what standard does the government have to meet in order to violate -- or to restrict privacy in this way, under what legal process and what mechanisms are in place for citizens to really defend these rights? It's really in troubled times when privacy protections, I think, are the most important, and it's inevitable sometimes that privacy and security concerns might come into tension.

WONGBut well-drawn laws, properly drawn laws that do respect due process, that respects human rights, should be able to advance both goals at once.

NNAMDIBack to the telephones. Here's Hal in Fairfax, Va. Hal, you're on the air. Go ahead, please.

HALYeah, thank you for taking my call, Kojo. I just want to comment -- was -- about Mr. Cameron over in Europe and his -- and also the recent incidents with the BART, you know...

NNAMDIIn San Francisco.

HALRight, in San Francisco -- that's exactly right -- where they were going to just shut down all the cell phones. I think that those two approaches indicate that governments are really confused as to, A, an understanding of technology and how it works, and, B, I mean, any kind of response, legal or otherwise, to it because as you look at the situation in London, they wanted to simply work to kind of spy on everyone.

HALHow would you even analyze all that data? And let's say everyone did send a tweet saying that they were going to be there or that they were going to do this or that. How would you prove that that person or that, you know, entity even, you know...

NNAMDIActually did it.

HAL...or whether they actually did it or -- I mean, it just opens up an entire can of worms as far as, you know, how would you convict that individual? How would you prove that it was actually them that sent the tweet or the Facebook message? I mean, it just seems like it's almost -- it's very draconian, would be the only response, which leads to the BART incidence, which is just simply shutting down all communications and saying...

NNAMDIWell, to prevent the event from taking place in the first place.

HALExactly, exactly, which that -- to me, that is the scariest thing, when governments start saying, well, we're just going to shut down all speech because we don't understand it, and we can't control it. And you could use this, which Cameron said almost that same thing. You could use this for some bad purpose, so we're just going to, you know, we're just going to shut it all down. I mean, that's -- to me, that's like "1984."

NNAMDIWell, Cynthia Wong, I heard a clip from a BART official, who said, your free speech rights end where our concern for public safety begins, and that's inside a subway station itself because a lot of bad things can happen to people in the subway station, whether intentionally or not. And our priority inside that station itself is always going to be public safety. What do you say?

WONGWell, it is true, I think, that BART authorities do have legitimate concerns about safety in the train system. And it is true under the law that the government is allowed to restrict speech in very precise, very specific incidences. It's when speech is going to incite unlawful acts. It's intended to incite unlawful activity, and is actually likely to incite imminent unlawful activity, which is a very, very high bar for government to meet.

WONGWhether the BART authorities are really justified here, you know, I think from a policy perspective, what they're doing and what they're saying that they can do -- which is be able to shut down the mobile network and also restrict speech within the "paid areas" of the BART system -- is very problematic. You know, it really -- it's hard to justify a complete shutdown of a general purpose tool as anything but a prior restraint on speech.

WONGYou're restricting completely innocent speech. You're restricting speech that may or may not have the intent of inciting unlawful activity. So I think it's very dangerous constitutional territory that we're in.

NNAMDICare to comment on that at all, Alessandro?

ACQUISTII would just comment about the fact that, going back to the issue of free speech, anonymity and privacy and face recognition, we used to feel that we are anonymous in a crowd. And, indeed, implicit in the First Amendment doctrine is the concept that anonymity is a means to protect free speech. But, really, what we are -- the technologies we are creating, effectively, are eroding this anonymity, even in a crowd, online and offline.

ACQUISTISo I do wonder, if we go away from the extreme case of face recognition online social networks used to find a criminal who is breaking into a store, looting it, and almost everyone will agree that we can use it for that. But if we, instead, consider the chilling effect that this technology may have, even on a free nonviolent protest or political rally out in the open, this is what concerns me about the potential usage of these technologies.

NNAMDIAnd I'm afraid we're out of time. Alessandro Acquisti is a professor at Carnegie Mellon University. Thank you so much for joining us.

ACQUISTIMy pleasure. Thank you for your time.

NNAMDICynthia Wong is the director of the project on Internet freedom at the Center for Democracy & Technology. Thank you for joining us.

WONGThanks again for having me.

NNAMDIAnd thank you all for listening. I'm Kojo Nnamdi.