Poynter:

The results of a new poll by “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,” says Dan Cassino, a professor of political science at Fairleigh Dickinson.

It’s still an open question as to cause or effect: Does watching Fox News make you stupid, or do you have to be stupid to watch Fox News to begin with?