In what should not be a surprise, a survey by Fairleigh Dickinson University found that while people who watched no news could answer 1.22 questions correctly,

…someone who watched only Fox News would be expected to answer just 1.04 domestic questions correctly — a figure which is significantly worse than if they had reported watching no media at all. On the other hand, if they listened only to NPR, they would be expected to answer 1.51 questions correctly; viewers of Sunday morning talk shows fare similarly well. And people watching only The Daily Show with Jon Stewart could answer about 1.42 questions correctly.