Today's NYT has an op-ed by Sam Wang and Sandra Aamodt on how certain false beliefs can be sticky, in part because we retain certain memories without retaining the source of the memory (a phenomenon dubbed "source amnesia"). An excerpt:
Journalists and campaign workers may think they are acting to counter misinformation by pointing out that it is not true. But by repeating a false rumor, they may inadvertently make it stronger. In its concerted effort to “stop the smears,” the Obama campaign may want to keep this in mind. Rather than emphasize that Mr. Obama is not a Muslim, for instance, it may be more effective to stress that he embraced Christianity as a young man.
. . .
In 1919, Justice Oliver Wendell Holmes of the Supreme Court wrote that “the best test of truth is the power of the thought to get itself accepted in the competition of the market.” Holmes erroneously assumed that ideas are more likely to spread if they are honest. Our brains do not naturally obey this admirable dictum, but by better understanding the mechanisms of memory perhaps we can move closer to Holmes’s ideal.