Iran, Mr. Cowie said, was one of a number of countries that have realized that “you don’t turn off the Internet anywhere — you make it less useful,” controlling which neighborhoods get it, for example.

Mr. Hassanpour, who was born and raised in Iran, agreed: “Iran does it in a localized way.”

So what is going on here? Certainly, blocking the ability of protesters to use the Internet and cellphones to plot has appeal for all kinds of leaders. In response to recent riots, the British government likewise was trying to figure out a way to gain access to social-networking services like Twitter, Facebook and BlackBerry’s messenger system, to stop potential rioters from organizing.

Speaking to Parliament this month, Prime Minister David Cameron made the case for a clampdown: “We are working with the police, the intelligence services and industry to look at whether it would be right to stop people communicating via these Web sites and services when we know they are plotting violence, disorder and criminality.”

That proposal, which the British government has backed away from recently, prompted defenders of social networking to point out that not all the organizing was for ill. Others point out that social networking can allow the authorities to follow what is being planned, and try to respond.

Mr. Hassanpour said he was inspired to ask his questions by the insight of a 2009 paper by Holger Lutz Kern of Yale and Jens Hainmueller of M.I.T. that looked at Germany during the cold war and tried to determine the effect of exposure to West German media on East Germans who were able to see West German TV.

The authors took some of the earnest interpretations of the supposed influence of Western media — like, the media gave “people behind the Iron Curtain hope and the assurance that the Free World hadn’t forgotten them,” and allowed Germans to “compare Communist propaganda with credible information from abroad” — and exposed these ideas to basic scrutiny.

Their conclusion, based on formerly classified East German surveys of young people and visa applications to leave East Germany, adjusted for other factors, was that “exposure to West German television increased support for the East German regime.”