Very interesting article in the Washington Post: "As the presidential campaign heats up, intense efforts are underway to debunk rumors and misinformation. Nearly all these efforts rest on the assumption that good information is the antidote to misinformation.

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. In some cases, correcting misinformation serves to increase the power of bad information.

In experiments conducted by political scientist John Bullock at Yale University, volunteers were given various items of political misinformation from real life. One group of volunteers was shown a transcript of an ad created by NARAL Pro-Choice America that accused John G. Roberts Jr., President Bush's nominee to the Supreme Court at the time, of "supporting violent fringe groups and a convicted clinic bomber."

A variety of psychological experiments have shown that political misinformation primarily works by feeding into people's preexisting views. People who did not like Roberts to begin with, then, ought to have been most receptive to the damaging allegation, and this is exactly what Bullock found. Democrats were far more likely than Republicans to disapprove of Roberts after hearing the allegation."