Daniel Kahneman: Judgement and Bias

Daniel Kahneman has won many awards and honours, but none more surprising, perhaps, than a Nobel Prize. Why is this surprising? Kahneman is, after all, one the most eminent and influential psychologists of his time. It is surprising because there is no Nobel Prize for psychology: Kahneman was co-recipient of the 2002 Nobel Prize in Economics ‘for having integrated insights from psychological research into economic science, especially concerning human judgement and decision making under uncertainty’.

In short, what Kahneman taught us was that, before he and his co-worker, Amos Tversky (who sadly died six years before the Nobel Committee considered this prize and so was not eligible), had started to study human decision making, all economic theories were based on the same, false assumption. Kahneman and Tversky taught us that human beings are not rational agents when we make economic decisions: we are instinctive, intuitive, biased decision makers.

And, if that sounds pretty obvious to us now, then we have Kahneman and Tversky, and their long walks together, to thank.

Daniel Kahneman


Short Biography

Daniel Kahneman was born in 1934 to Lithuanian emigré parents living in Paris (although he was born when they were visiting family members in Tel Aviv). When Nazi Germany occupied France, the family went on the run, ending up after the war in what was then (1948) Palestine under the British Mandate, shortly before the formation of the State of Israel.

In 1954 he gained his BSc from the Hebrew University, in Psychology and Maths, and joined the psychology department of the Israeli Defence Forces, helping with officer selection. Four years later, he went to the University of California, Berkeley, where he was awarded a PhD in 1961. He returned to the Hebrew University in 1961.

It was in 1968, while hosting a seminar, that he met Amos Tversky. They started collaborating shortly afterwards. Their fertile discussions often involved thought experiments about how we make decisions and judgements, uncovering in themselves a series of heuristics – or thinking shortcuts – which they went on to observe in controlled laboratory experiments. Their collaboration continued until Tversky’s death in 1996.

In that time, they collaborated with other researchers, most notably, Paul Slovic and economists Richard Thaler and Jack Knetsch. Their many insights into how we make judgements and the application to economic decision-making eventually led to the Nobel Committee recognising Kahneman with the 2002 Sveriges Riksbank Prize in Economic Sciences in Memory of Alfred Nobel.

Kahneman’s 2011 book, Thinking, Fast and Slow is a summary of a remarkable life’s work. If the ideas are new to you, they may well rock your world. It is not an easy read, but it is remarkably well-written for an intelligent lay audience. Even if Kahneman’s work is familiar to you, this book will repay close reading.

Kahneman’s Ideas

There is far too much in Kahneman’s work to even begin to summarise it, so I want to focus on three biases that he discovered, which have a profound impact on the choices we make; often leading us far astray.

The Anchoring Bias

The first information we get biases any subsequent choices we make. Your father was right, or your mother or anyone else who told you at a young age that first impressions count. Systematically, the human brain takes the first information it receives, and creates an interpretation of everything else that is anchored in the inferences it draws from that first impression. In management terms, this accounts for the horns and halo effect, that biases us to seek and spot confirming evidence for our pre-existing assessment.

The Representativeness Bias

Who is a more likely person to find working in a car repair shop, changing your brakes? Is it A: a young woman with blond hair and pink eyeliner, or B: a young woman with blond hair and pink eyeliner, whose father owns the car repair shop?

If you think B, you have fallen for representativeness bias. The story makes more sense in our experience, doesn’t it? A young woman with blond hair and pink eyeliner is not a person you’d expect to see in that environment. But a young woman with blond hair and pink eyeliner, whose father owns the car repair shop, may feel right at home. But statistically, this is rubbish. For every young woman with blond hair and pink eyeliner, only a small proportion will also have fathers who own a car repair shop.

The Availability Bias

Recent events bias our perception of risk. They are more available to recall and hence have a stronger impact on our intuition than do counter examples. The classic example is perceptions of risk of train travel, after a train crash. Trains are safe: they rarely crash. Cars crash a lot: there are many accidents every day. But they are rarely reported, so we have no immediate intuitive sense of the statistics.

The Impact of Kahneman’s Work

Kahneman’s work has had a huge impact. Decision theory existed before he came along, but he and Tversky revolutionised it. But it was Kahneman, along with Tversky, Knetsch and Thaler who pretty much invented the discipline of behavioural economics – and perhaps the relationship that drove that development was the friendship between Thaler and Kahneman.

Now Behavioural Economics infuses much of public policy and social influence that corporations try to exert over us. Thaler’s book, Nudge (with Cass Sunstein) is a best seller and Thaler and Sunstein both advise Prime Ministers and Presidents. Next time you get a document from Government, or go into a store, and you find yourself complying with their wishes without thinking, there is a chance that you have been ‘nudged’. And the roots of these ‘choice architectures’? The roots are in understanding our heuristics and biases. And that was Kahneman’s contribution.

Kahneman at TED

Here is Daniel Kahneman, talking about how we perceive happiness and discomfort.



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