Shankar Vedantam wrote in the Washington Post 15 Sep 2008 about The Power of Political Misinformation, illustrating with a couple of well-known examples of misinformation (you’ll recognize them), and continuing:
Nearly all these efforts rest on the assumption that good information is the antidote to misinformation.Countering bad information directly just reinforces it.But a series of new experiments show that misinformation can exercise a ghostly influence on people’s minds after it has been debunked — even among people who recognize it as misinformation.
Chris Mooney wrote more about why that is in Mother Jones 18 April 2011, The Science of Why We Don’t Believe Science: Continue reading