Here is a 2014 article by Chris Mooney that tries to explain why Fox News viewers are more misinformed than other news consumers. The piece is an excerpt from his book, “The Republican Brain: The Science of Why They Deny Science–and Reality“.
Much of the misinformation is deliberate on the part of Fox News, but conservatives are also psychologically predisposed to seek out information that confirms their existing biases. Those two things form an amplifying feedback loop.