Over-rating our knowledge - why you should be covered in lemon juice when robbing a bank



He decided to put lemon juice on his face so the CCTV cameras couldn’t see him. No one had said it would work, but McArthur Wheeler reasoned that it must do. Obviously if lemon juice was used as invisible ink, then it would make him invisible too.

He was no fool, though. Before the robbery, McArthur checked his theory by covering himself in lemon juice then taking a selfie with his Polaroid camera (it was 1995). The photo came out completely blank (maybe he hadn’t taken the lens cap off) yet this convinced him he was right - he would indeed be invisible to the banks’ cameras.

He robbed two banks that day, and a couple of hours later the police took the security camera images of him (regrettably the lemon juice hadn’t worked!) and got them on the eleven o’clock news. Soon after someone rang saying they recognised the robber – it was McArthur Wheeler. A short while later McArthur was sitting in a police cell, expressing amazement that the ‘invisible ink’ hadn’t made him… well… invisible.


Learning from the bank robber

McArthur’s story fascinated (and amused) psychologists Dunning and Kruger. How, they wondered, could he have been so confident that he would be invisible – or that a blank photo proved his theory? Why had he been so sure of his idea?

They began to carry out studies, and from them concluded that indeed, like McArthur Wheeler, most people with very little understanding of a subject tend to over-estimate their level of knowledge.

This observation should come as no surprise to any therapist who has been in practice for a while. It was demonstrated convincingly to me when Paul McKenna first appeared on TV: many clients would lecture me on the nature of hypnosis, and if I gave them information not fitting their beliefs they would patronisingly correct me. They knew, because they’d seen ‘it’ on TV.

Now I’m an open-minded person, and feel that in most areas of life almost anyone might contribute a valuable idea – inspiration comes to us all at times. But this wasn’t inspiration; these clients had made false assumptions about a programme of entertainment, and so their certainty of ‘rightness’ amazed me.

I asked myself, if I saw a ‘Surveyor’ in a TV comedy show would I then feel knowledgeable enough to lecture, say, a Quantity Surveyor, condemning his knowledge and skills simply because of assumptions I’d made? Surely I would be more respectful and ask questions instead? But the studies suggested that most of us would be telling the Surveyor about surveying – just as my clients were telling me about hypnosis.


What about experts?

As an aside, Dunning and Kruger’s research also showed that experts had the opposite problem – they tended to underestimate their own knowledge and skills. The researchers speculated this was because experts found what they did easy and so assumed it would be so for most others.


Too stupid?

But going back to people like McArthur, why do those with so little knowledge over-value their scant resources? Dunning and Kruger concluded that, ironically, we need a lot of knowledge to be able to recognise our own ignorance. Some people have described the problem as:

‘Too stupid to know you’re stupid’!

This is certainly not the way researchers would put it, but it conveys the idea succinctly, if unkindly. Really, though, it’s usually not about stupidity, it’s about our not having sufficient information to realise how limited our knowledge is.


Learning that you don't know

It seems if we have a great deal of knowledge we can achieve a more realistic view of what we know. I remember meeting a Professor who had continued to study throughout his life, and now had a number of degrees and PhDs. He was one of the brightest people I had ever met. Curious, I asked him what he felt was the most important thing he’d learned. He replied:

‘My learning has taught me how little I know.’

The people who are ‘too stupid to know they are stupid’ aren’t in such a fortunate position.

This over-valuing of our sparse knowledge (now known as the Dunning-Kruger Effect) can be seen everywhere. It shows itself in such things as talent programmes, where people without talent may be outraged when told that their tuneless performance is not good enough.

Recently a Donald Trump supporter wrote on facebook a barely literate comment, completely ignorant of the issues, so when someone retorted sarcastically:

‘Your deep understanding of the subtleties of politics is matched by your skilled and thoughtful command of grammar and style’

you might have expected the Trump fan to give a raving, abusive response. Instead, he gave these cutting remarks a ‘like’! The Trump supporter didn’t have enough understanding to know he was being insulted.


What about therapists?

What’s this got to do with working as a therapist? Well, both the 'expert effect’ and the 'ill-informed effect' surely must be a lesson to us.

When we really do have considerable knowledge or skill (such as with a particular technique) then we should try to appreciate it by considering all we’ve done to acquire our knowledge – this will help us to have confidence in our actions and appropriately value ourselves as therapists.

On the other hand, in some therapy areas we may have insufficient knowledge to help clients, and so must willingly refer on. If we have any doubts about our knowledge we can realise that the Dunning-Kruger Effect suggests we should lean towards referral. We all have limits to our knowledge, and may be fooled by the Dunning-Kroger Effect into feeling we know more than we do. No one wants to be another McArthur Wheeler.

PS Anyone want to buy my invisible car? You can wash the lemon juice off after you’ve paid me for it.


Other pages you would like to read:

  Becoming a Mirror

  Can you become brighter?