We’ve known it all along, but now we have numbers.

People who watch Fox News are 18 points dumber than people who watch no news at all.

But the real finding is that the results depend on what media sources people turn to for their news. For example, people who watch Fox News, the most popular of the 24-hour cable news networks, are 18-points less likely to know that Egyptians overthrew their government than those who watch no news at all (after controlling for other news sources, partisanship, education and other demographic factors).

Fox News watchers are also 6-points less likely to know that Syrians have not yet overthrown their government than those who watch no news. “Because of the controls for partisanship, we know these results are not just driven by Republicans or other groups being more likely to watch Fox News,” said Dan Cassino, a professor of political science at Fairleigh Dickinson and an analyst for the PublicMind Poll. “Rather, the results show us that there is something about watching Fox News that leads people to do worse on these questions than those who don’t watch any news at all.”

The study also found that people who read the New York Times of even USA Today show an 11 point improvement in correct information over those who watch no news at all.

But the Grand Prize winner:  The Daily Show.

… but the biggest aid to answering correctly is The Daily Show with Jon Stewart, which leads to a 6-point decrease in identifying the protestors as Republicans, and a 12-point increase in the likelihood of giving the correct answer.

Yep, Jon is off this week and I already feel dumber.

Thanks to Sandy for the heads-up!