A recent survey of New Jersey residents found that people who watched Fox News were less likely to know the outcomes of the recent uprisings in Egypt and Syria--not just less than people who got their news from other sources, but less than people who didn't follow the news at all. Is this part of a general pattern? I found a Pew survey from 2010 which had several questions about current affairs: which party had a majority in the House of Representatives, which position Eric Holder had, which company Steve Jobs headed, and which country had recently had a volcanic eruption that disrupted air travel. It also had questions about how frequently people watched or listened to various programs. I computed scores of how often people followed liberal (Keith Olbermann, Chris Matthews, Jon Stewart, Stephen Colbert, and Rachel Maddow) or conservative (Sean Hannity, Bill O'Reilly, Rush Limbaugh, and Glenn Beck) programs.
Watching both kinds of programs was associated with greater knowledge (even controlling for education). The association with conservative programs was actually slightly bigger, although the difference was not statistically significant. And both had stronger associations with knowledge than reading newspapers and news magazines. (I say associations rather than effects, since there's no way to know how much of the information people got from the programs). So apparently Fox News doesn't always make people less informed. On the other hand, the comparison suggests that there was something wrong with their coverage of the Middle East uprisings--their audience is not just generally ignorant of basic political facts.