The Washington Post has a depressing article
about the difficulty of myth-busting. Experiments by Norbert Schwarz at the University of Michigan reveal that a few days after telling people a rumor is false, many of those people will have misremembered what they were told and think the rumor is true. The crux of the problem is that:
Denials inherently require repeating the bad information, which may be one reason they can paradoxically reinforce it.
Other psychologists have found that hearing the same thing again and again from the same source can actually trick the brain into thinking information is more credible, as if the information came from many sources:
People are not good at keeping track of which information came from credible sources and which came from less trustworthy ones, or even remembering that some information came from the same untrustworthy source over and over again. Even if a person recognizes which sources are credible and which are not, repeated assertions and denials can have the effect of making the information more accessible in memory and thereby making it feel true.
So what can myth-busters do? Unfortunately, not much. The only recommended tactic is to debunk rumors by not referring to the original rumor at all, and instead offering a completely different new assertion. For instance:
Rather than say, as Sen. Mary Landrieu (D-La.) recently did during a marathon congressional debate, that "Saddam Hussein did not attack the United States; Osama bin Laden did," Mayo said it would be better to say something like, "Osama bin Laden was the only person responsible for the Sept. 11 attacks" -- and not mention Hussein at all.
It's going to make it pretty hard to operate a myth-busting website if one of the rules is that I can't mention the myth I'm debunking. (Thanks, Joe!)