Humanizing Rules

CHAPTER 6BEHAVIOURAL DRIVER 1: OUR EXPERIENCE AND KNOWLEDGE

Invisible Ink

In 1995, a large middle‐aged man called McArthur Wheeler robbed two Pittsburgh banks at gunpoint in broad daylight. Unusually for a bank robber, Wheeler didn't wear a mask or any form of disguise. He even smiled at the surveillance cameras. Unsurprisingly, he was arrested later that day. When the police showed him the video tapes of him robbing the banks, Wheeler couldn't understand how they had managed to find him. “But I wore the juice,” he told them. It transpired that Wheeler had discovered that you could make invisible ink using lemon juice. He had then taken his newfound knowledge and, for some reason, concluded that it would also serve to make him invisible. Having covered his face with it, he thought he had the perfect disguise.

Two academics, David Dunning and Justin Kruger, read about the story and were intrigued. How, they wondered, could someone be quite so stupid? Dunning and Kruger decided to find out and undertook some research. What they discovered – later published under the title “Unskilled and unaware of it”¹ – was a cognitive bias called the Dunning–Kruger Effect. In simple terms, it's the idea that unskilled people make poor decisions. Their incompetence also means they lack sufficient “metacognitive ability” – what you and I might call intelligence – to realise it.

The Dunning–Kruger Effect is pervasive. For extreme examples of it, I recommend visiting the Darwin Awards website. ...