NPR viewers are most knowledgeable, and Fox News viewers are the least.
“They found that someone who watched only Fox News would be expected to answer 1.04 domestic questions correctly compared to 1.22 for those who watched no news at all. Those watching only "The Daily Show with Jon Stewart" answered 1.42 questions correctly and people who only listened to NPR or only watched Sunday morning political talk shows answered 1.51 questions correctly. In terms of international news, people correctly answered an average of 1.8 of 4 questions.”
Frankly, there is a whole lot of noise in the wide girth called the news channel. It is broad and deep.
Noise is unwanted messaging. People naturally have broad and varied interests with some particular interests. If questions are asked about celebrities, people may or may not care because it is not a life necessity. People may care about government, but when it is perceived as consistently broken and nonresponsive, messages may be lost on deaf ears.
People tend to listen to and hear sources with which they are comfortable. Therein lies a trap for unthinking and lazy minds.
Interpreting the news takes listening and thinking, something for which there is less discretionary time when people are working so hard to attend to necessities, like the Super Bowl, for instance.
Really, many news organizations feature people who have no credentials for speaking about news content. Uncredentialed people talking about things about which they do not know produces a whole lot of noise in the channel.