One urban myth that has resurfaced recently is that of the car park attendant at Bristol Zoo who dutifully collected parking fees for 24 years only to be discovered to have been a conman who pocketed them all for himself.

There's a good reason why so many people believed this story. It's because we do tend to take people at their self-assessment and self-presentation: if a man says he's something, and he looks and acts the part, we tend to believe him.

For example, in Influence, Robert Cialdini describes an experiment in which a man asked passers-by to give a third man money to pay a parking meter; passers-by were far more likely to comply when the man was dressed as a security guard than when he was dressed normally. And in a separate experiment, Cameron Anderson and Sebastien Brion have found that people rate over-confident folk as being more competent than they are: we tend to believe people's images of themselves.

All this is no mere curiosity of psychologists' experiments. It has real political effects. For example, George Osborne has contived to present himself as being in control of the public finances and his opponents as "deficit deniers" even though his policies have failed in their own terms to cut the deficit as much as expected. David Cameron's promise last week to "end discrimination and finish the fight for real equality" was seen by some as a progressive move to the centre ground, oblivious to the fact that Tories' actual policies aren't quite so egalitarian. And the SNP has won huge support by claiming to be progressive and anti-austerity even though they are not.

All these are examples of voters and pundits believing the presentation.

I suspect that there are four mechanisms which combine to produce this.

One is that people in successful societies tend (pdf) to instinctively trust (pdf) each other. This is by no means a bad thing: trust is essential for many economic transactions and thus a contributor to healthy economies as well as good societies.

Secondly, there is simple deference. As Adam Smith famously said:

We frequently see the respectful attentions of the world more strongly directed towards the rich and the great, than towards the wise and the virtuous. (Theory of Moral Sentiments I.III.29)

I suspect that one contributor to this is the outcome bias: we assume that because someone has gotten rich or won elections they must have superior knowledge and ability, and so under-rate the role of luck.

Thirdly, as Cialdini says, there is a "deep-seated sense of duty to authority within us all"; from childhood we are brought up to identify authority - teachers and parents - with superior knowledge. However, as Stanley Milgram's famous experiments - along with much of human history - have shown, this can have terrible effects.

Finally there's a confluence of confirmation bias and social proof: once we believe something of somebody, we interpret ambiguous evidence as corroboration of that belief, and if enough people believe something of someone, then others will follow them.

Through these mechanisms, reputations can be won even if they are undeserved. And once a man has a reputation, he can use it to con people. That mythical car-park attendant and George Osborne have something in common.