Backfire effects pick up strength when you have no particular reason to trust the person you are talking to. This perhaps explains why climate sceptics with more scientific education tend to be the most sceptical that humans are causing global warming.

The irony is that understanding backfire effects requires that we debunk a false understanding of our own. Too often, argue Lewandowsky and Cook, communicators assume a 'deficit model' in their interactions with the misinformed. This is the idea that we have the right information, and all we need to do to make people believe is to somehow "fill in" the deficit in other people's understanding. Just telling people the evidence for the truth will be enough to replace their false beliefs. Beliefs don't work like that.

Psychological factors affect how we process information – such as what we already believe, who we trust and how we remember. Debunkers need to work with this, rather than against if they want the best chance of being believed.

The most important thing is to provide an alternative explanation. An experiment by Hollryn Johnson and Colleen Seifert, shows how to persuade people better. These two psychologists recruited participants to listen to news reports about a fictional warehouse fire, and then answer some comprehension questions.

Some of the participants were told that the fire was started by a short circuit in a closet near some cylinders containing potentially explosive gas. Yet when this information was corrected – by saying the closet was empty – they still clung to the belief.