Asleep at the wheel: what makes us human is our irrationality

We are drawn to some types of information over others, our past experiences shape our present-day judgements and our emotional and physical states affect the choices we make.

Pulling an all-nighter won't help with decision-making the morning after. Photo: Thomas Dworzak/Magnum Photos
Pulling an all-nighter won't help with decision-making the morning after. Photo: Thomas Dworzak/Magnum Photos

I am 14 years old, sitting in my first economics class. We are taught that we make decisions as rational men, Homo economicus. That we objectively weigh up pros and cons and coolly evaluate information.

Rational men. Hmmm. Not only does economics in one swoop ignore my entire sex, it also assumes that we are robotic, dispassionate creatures.

We are not.

What makes us human is our irrationality – the way we are drawn to some types of information over others, the way our past experiences shape our present-day judgements, the way our emotional and physical states affect the choices we make.

Take colour. It plays a surprisingly signi­ficant role in the way we evaluate situations. Men rate women as more attractive if they see their photographs set against red backgrounds rather than white, grey, blue or green. Waitresses are tipped more when they wear red. Football referees are more likely to give penalties to teams wearing black strips than to those in other colours.

Language – the choice of words, images and metaphors used – also has a huge impact on the judgement calls we make. I may not fall for politicians’ fear-mongering, but beauty companies have at times caught me out. In my bathroom cabinet are products that “correct” dark spots, “fight” ageing and can infuse my eyes with “youth”. Really, though?

And how about the British study which revealed that when two groups of psychiatrists were told the same story of a young man who had attacked a train conductor, the only difference being the attacker’s name, they provided different diagnoses depending on what they believed him to be called? When the psychiatrists thought the attacker was called Matthew, they were more likely to diagnose him with schizophrenia. When they thought he was called Wayne, they were more likely to diagnose him with a drug problem.

Time and time again we are affected by factors of which we are not even aware. Time and time again we behave irrationally. It’s not just the way information is presented to us of which we need to be mindful. We need to be aware, too, of the impact of our physiological and psychological state on the choices we make.

If we’re anxious, we are more risk-averse. Stress makes us prone to tunnel vision, less likely to take in all the information we need. When we’re happy we take more risks, are more trusting, more generous. It’s why a country’s stock market tends to rise off the back of a national team’s win at football. (Not something England needed to worry about this year, sadly.)

If we’re tired, that messes with our decision-making. If you’ve ever pulled an all-nighter you will know the symptoms of sleep deprivation all too well: difficulty concentrating, brain like cotton wool, memory lapses. But did you know that if you go 24 hours without sleep or spend a week sleeping only four or five hours a night, it’s as if you’re making decisions drunk?

Are you the type who skips breakfast? If so you might want to rethink that. Fascinating research in Israel on why judges decided to grant prisoners parole showed that the main determinant wasn’t the applicant’s gender or ethnicity, nor even the type of crime, but whether the judge had recently eaten.

If you went before the judge just before they’d had their mid-morning snack . . . disaster. Zero per cent chance of getting parole. Immediately after that snack: 65 per cent. Just before lunch . . . disaster again. Only a 10 per cent chance of getting parole. Immediately after lunch: 65 per cent.

And if you’re feeling horny, well, you probably want to wait before you make that important call. When Canadian male undergraduates were given one of two images to look at – either a Victoria’s Secret model or a neutral object, a rock – and then asked to make a financial decision, the guys who’d been looking at the Victoria’s Secret model made significantly worse financial decisions than those who’d been looking at a rock.

What makes us human is our irrationality – and that the choices we make are influenced by a whole host of factors that have nothing to do with the decision at hand.

What makes us smart is our ability to acknowledge this, and then actively challenge ourselves and our immediate impulse. 

The “What Makes Us Human?” series is published in partnership with the Jeremy Vine show (BBC Radio 2)

Noreena Hertz’s “Eyes Wide Open: How to Make Smart Decisions in a Confusing World” is out in paperback (William Collins, £8.99)

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