The executive summary:

Debunking myths is problematic. Unless great care is taken, any effort to debunk misinformation can inadvertently reinforce the very myths one seeks to correct. To avoid these "backfire effects", an effective debunking requires three major elements. First, the refutation must focus on core facts rather than the myth to avoid the misinformation becoming more familiar. Second, any mention of a myth should be preceded by explicit warnings to notify the reader that the upcoming information is false. Finally, the refutation should include an alternative explanation that accounts for important qualities in the original misinformation.

The handbook has six one-page pieces with a seventh page providing the references. Clearly written, with reinforcing graphics, this is a clear and easy read (which helps sets an example for good myth-busting). Here, in brief, are the six points

Debunking the first myth:  Sadly "mud sticks"

Those in the reality-based world often deal with things in the 'information deficit' model.  If people only knew the facts and had more information, the problem would be solved. In dealing with myths, we have to engage the thinking and thought processes rather than simply the database of information.

A common misconception about myths is the notion that removing its influence is as simple as packing more information into people's heads. This approach assumes that public misperceptions are due to a lack of knowledge and that the solution is more information - in science communication, it's known as the "information deficit model". But that model is wrong: people don't process information as simply as a hard drive downloading data.

And, worsening this challenge is that once the mis (or dis) information is there, it is nearly impossible to totally dislodge it from people's thinking. Worse off, of course, is that debunking the myth efforts, if poorly done, can and will) "make matters worse.

So this handbook has a specific focus - providing practical tips to effectively debunk misinformation and avoid the various backfire effects.

The Familiarity Backfire Effect

Sigh, to debunk the myth requires mentioning it?  Oops, not necessarily. And, more importantly, if you have to mention it make sure to do so within a context. "Your debunking should begin with the facts", not emphasize (e.g., no bolding people) the myth, and provide a context (an alternative explanation) of how the myth misleads.  E.g., sandwich the myth with facts and a factual explanation of why it is a myth, subordinating the 'myth' itself into a minor role in the conversation.

Overkill Backfire Effect

If one fact is good, 100 must be great? Yet again, a myth.  At some point, we hit overload "because processing many arguments takes more effort than just considering a few.  A simply myth is more cognitively attractive than an over-complicated correction."

The solution is to keep you content lean, mean and easy to read.

The Worldview Backfire Effect

In essence, this really says 'give up hope' for the most doctrinaire since they will struggle (consciously and unconsciously with the Confirmation Bias) to come up with ways information reinforces their position and deride/denigrate anything that doesn't fit (and fulfill) their weltanschauung.

This was demonstrated when Republicans who believed Saddam Hussein was linked to the 9/11 terrorist attacks were provided with evidence that there was no link between the two, including a direct quote from President George Bush.11 Only 2% of participants changed their mind (although interestingly, 14% denied that they believed the link in the first place). The vast majority clung to the link between Iraq and 9/11, employing a range of arguments to brush aside the evidence. The most common response was attitude bolstering - bringing supporting facts to mind while ignoring any contrary facts. The process of bringing to the fore supporting facts resulted in strengthening people's erroneous belief.

Since the backfire effect is strongest in those with already fixed views, this means that

outreaches should be directed towards the undecided majority rather than the unswayable minority

More importantly, "messages can be presented in ways the reduce the usual psychological resistance."  Use self-affirmation to build confidence that enables people to question themselves and frame discussions in ways appropriate to the audience.

Self-affirmation and framing aren't about manipulating people. They give the facts a fighting chance.

Mind the Gap

An interesting item, which I'd never concerned before the Handbook, is that the debunking effort creates a void (a gap in people's mental model) and nature abhors a vacuum.  For effective debunking, "your debunking must fill that gap" with an alternative (truthful) explanation.

An FYI from this section, "if your content can be expressed visually, always opt for a graphic in your debunking."

Anatomy of an effective debunking

Bringing all the different threads together, an
effective debunking requires:

   
• Core facts--a refutation should emphasise the facts, not the myth. Present only key facts to avoid an Overkill Backfire Effect;

   
• Explicit warnings--before any mention of a myth, text or visual cues should warn that the upcoming information is false;

   
• Alternative explanation--any gaps left by the debunking need to be filled. This may be achieved by providing an alternative causal explanation for why the myth is wrong and, optionally, why the misinformers promoted the myth in the first place;

   
• Graphics - core facts should be displayed graphically if possible.

In short, consider the Debunking Handbook a must read and a must keep reference.