The Backfire Effect is one of the most infuriating new developments in politics and one of the major differences between liberal and conservative voters.
Simply put, conservatives are too stupid to evaluate between truth and falsehood. They rely upon the "authority" of the speaker and if a speaker they trust lies, and that lie is refuted by a liberal, they automatically gravitate toward the lie because they are not capable of evaluating the truth and instead default to the (totally untrustworthy) authority they trust.
This is why Republican candidates at the debates have adamantly stood by their lies even when stone-cold busted by facts and figures. By sticking to their guns when refuted with actual facts they are actually making stupid Republicans believe the lie they told.
Journalists help the Backfire Effect along quite a lot by 1) pretending it doesn't exist, and 2) pretending it works equally among all people. It does not. Some of all people default to the first thing they learned, true or not, but only conservatives become more likely to believe the lie when it is refuted.
You can see the Backfire Effect at work in the statistics above. Democratic candidates, playing to their own audience, have no incentive to lie and can suffer greatly for being deceptive (see Gary Hart, John Edwards). Conversely, Republican candidates are rewarded for lying, and you can see it in the stratification of the candidates from most dishonest (Trump) at the top to least dishonest at the bottom (Kasich).
Depending on who wins which nomination, some candidates may have an incentive to adjust their delivery by lying more or less, but at this point neither can do much adjusting. Trump must try his hand at telling the truth but his prior statements will always be used against him. Bernie Sanders and Hillary Clinton, on the other hand, would benefit from not refuting false statements by Trump, which is its own form of dishonesty.
Thus we are all the victims of the use of fear and dishonesty in political statements. Nobody wins, except the most evil ones who can successfully wiggle like a catfish in the hippo-poop-mud of a drought-stricken African pond. Great.