This Army Exercise Was So Useless It Inspired A Psychological Theory

israel defence force idf recruitNew recruits at the IDF.

Photo: via Creative Commons

Long before he won the Nobel Prize for Economics, Daniel Kahneman was a psychology officer for the Israeli Defence Force. He got a lot out of his time in the army too, including inspiration for the illusion of validity.Kahneman invented this concept after evaluating officer candidates in a “leaderless group challenge,” according to his book Thinking, Fast And Slow.

This was a drill where 8 candidates who didn’t know each other, with no markings of rank, were instructed to carry themselves and a long log over a six-foot wall without touching the wall. The test required ingenuity and teamwork (getting the eighth man across typically involved him jumping at the log held at an angle by the seven men on the other side) and often resulted in failure.

In the process, the test was supposed to reveal who was a good leader.

Kahneman and his colleagues felt like it was very effective test: “We were completely confident in our evaluations and felt that what we had seen pointed directly to the future.”

Unfortunately, it didn’t work:


Despite the failure of the test, the IDF continued using it. What’s more, Kahneman and his colleagues continued to feel confident with each prediction that they were getting it right.

This hypocrisy inspired a breakthrough:


Wikipedia describes the illusion of validity as “a cognitive bias described by Amos Tversky and Daniel Kahneman in which consistent evidence persistently leads to confident predictions even after the predictive value of the evidence has been discredited.”

Kahneman’s book also discusses the cognitive failures of punditsfinancial advisorsamateur investors, and pretty much everyone.

Don’t miss: 57 behavioural Biases That Make Us Think Irrationally >

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