Monday, February 20, 2006

Gut thinking

We humans often pride ourselves on our rationality, and on our ability to make complex decisions through reasoning power. In recent decades, however, the role accorded to reason in driving our decisions and behaviour has been called into question by many psychologists.

Experiments have revealed that our decisions seem to be driven by an assortment of biases and heuristics — mental rules of thumb that help us get to a reasonable answer if a relatively short amount of time. And these heuristics need not be conscious. Indeed, another relevant trend in psychology has been a greater appreciation of unconscious processes in shaping our decision-making and behaviour. These are not unconscious desires or wishes in the Freudian sense, but processing rules that are not necessarily consciously monitored.

Much of the study of heuristics has highlighted the systematic ways in which human reasoning can veer into illogic. For instance, if you ask people how many words, in four pages of a novel, will have ‘ing’ as an ending, they typically give a higher number as an answer than if you ask how many words will have ‘n’ as the second-to-last letter in four pages from the novel (an example of what is called the availability heuristic, but I won’t go into detail here). And this does not make logical sense.

Similarly, what’s called the ‘representativeness heuristic’ can lead people astray. This is illustrated by looking at people’s answers to questions about the likely career of a hypothetical woman named Linda:

“Linda is 31 years old, single, outspoken, and very bright. She majored in philosophy. As a student, she was deeply concerned with issues of discrimination and social justice and also participated in antinuclear demonstrations.”

After reading this description, people were asked to rank the likelihood of various possible future life outcomes for Linda, the most important two (for the purposes of the study) being ‘bank teller’ and ‘bank teller and active in the feminist movement’. Most people think that the latter possibility is more likely, even though it is statistically more likely that she would be just a bank teller, rather than both a bank teller and a feminist activist. This is known as the conjunction error, in which the occurrence of two independent characteristics is deemed more likely than one alone (and statistics says this isn’t so).

So much for how we actually reason: when it comes to thinking, we’re frequently far from logical. But what about when we put our mind to thinking about a decision or problem? Surely more thinking is better, and more likely to lead to the best solution or choice?

Well not according to some research published in last week’s Science. Ap Dijksterhuis and colleagues at the University of Amsterdam in the Netherlands have found that too much thinking can get in the way of reaching a good decision — perhaps counter-intuitively, this is even more true when the decision is more complex. Conscious deliberation seems to be better suited to making simple decisions, such as what brand of kitchen utensil to buy, but for the more complex and important decisions in life, perhaps such as buying a house or car, less thinking may mean a better decision.

In one set of experiments, participants were provided with a choice of four cars. The task was to pick the best car out of the range on the basis of details about four characteristics of the cars, such as mileage and legroom. Each person had four minutes to mull over the problem, and most participants picked the same car — the one that was in fact best on the basis of the listed attributes. In a variation of this experiment, the cars had 12 characteristics, making the decision-making process more complex because there were more factors to take into account. And this increased complexity of the decision was reflected in people’s choices: after four minutes thought, only 25% picked the car with the best attributes, or no better than merely picking at random. Perhaps understandably, a more difficult choice made for worse decisions.

In the final condition, the participants, after reading about the cars and the 12 attributes, were asked to solve anagrams for four minutes before making their choice of car. And the effect of this distraction? To increase their skill in identifying the best car — after taking their minds off thinking about the car by solving anagrams, more than half of the study subjects picked the best car. This suggests that at least in some cases less explicit, conscious deliberation, and a greater reliance on unconscious mental processes, can help make for better decision-making in complex situations.

Dijksterhuis and colleagues also explored this issue in a more real-life situation: shopping for simple items of clothes and kitchenware, compared with furniture shopping at IKEA (which, being a bigger investment, and relating to home design, can be expected to be a more weighty and complex choice to make). The researchers stopped shoppers leaving IKEA and the shop selling kitchen utensils and other smaller items, and asked them how long they had spent mulling over their decisions. They then called the shoppers up a couple of weeks later to see how happy they were with their purchases. Whereas the people that spent longer thinking the about their small purchases were generally happier with what they had bought, the reverse was true of IKEA shoppers — more thought led to a less satisfactory choice.

One possible reason for the poor performance when making more complicated decisions is that the brain can only keep so much information accessible to consciousness. So perhaps partial or muddled information gets factored into conscious decisions, which then turn out to be bad. This study illustrates that complexity might be a key factor determining whether conscious deliberation or something more gut-based (meaning not consciously thought through, and perhaps emotionally laden) is the most appropriate path to a decision.

But it would be rash to rule out the role of thinking altogether in coming to important decisions. It is quite possible that taking all the relevant information into account, rolling it around in your head for a while, and letting it be unconsciously processed may lead to good decisions. In fact, this is what Daniel Kahneman, a Nobel Prize-winning economist for his work on decision-making, says: “I would not advise people to buy a car or house without making a list. You will probably improve your intuitions by making a list [of pros and cons] and then sleeping on it.” Dijksterhuis agrees: for important decisions, he finds out the relevant facts and focuses his full attention on the decision. Then? “I sit on things and rely on my gut.”

This research might also illuminate the almost magical ability of doctors, fire-fighters and jazz musicians to make accurate on-the-spot decisions about medical care, plans of action, and note choice, for example. It is not that these people are better off for having less knowledge of information with which to consciously work, but that their expert knowledge can be accessed unconsciously and extremely rapidly, through years of experience and practise.

So next time you have a small decision to make, think about for a reasonable time, and go for it; for the bigger ones, have a think, weigh up the options, then think about something else for a while. When you come back to make your decision, it may just make the best choice (or at least one you’ll be happy with).


Blogger Potentilla said...

Have you any suggestions for a couple of particularly good and recent-ish books in this general area? What did you think of "Blink?"

BTW, I really enjoy your blog and read most posts several times. As your posts are carefully-crafted, I assume you prefer comments that are ditto, so I only comment if I have something specific to say - or ask. I'm still thinking about zombies.

11:13 am GMT  
Blogger Steve said...

About the conjunction error: it always strikes me that when offered the choice of which is more likely, 'A' or 'A and B', the former option gets read as 'A and NOT B' by virtue of being alongside the latter option. In which case, it's not a logical fallacy in the way described.

Studies such as the car-buying or IKEA shopping experiments strike me as pretty far-fetched in the conclusions drawn. How is the 'best' decision defined? Best by who's criteria? An across the board standard, or measured with respect to each participant? If only one car is considered best, how is it found? For example, plenty of people want to drive BMWs. This would be the best car in many selections by road handling, status etc. For me, I wouldn't go near one with a bargepole.

If the best is measured with respect to each participant, how is that found, and wouldn't that just be the one they chose at the time. And what is the time-frame for the best choice? To my mind there are too many 'dimensions' to a question like this, and the experimental apparatus used to answer the question is way too crude. For example, clothes are labelled a small item next to household furniture. I know many people for which the reverse is true.

7:03 am GMT  
Blogger Dan Jones said...

Potentilla, glad you’re enjoying the blog and still visiting. As for comments, I’m happy to read anything from short messages or agreement or disagreement to long replies. It’s just good to know how people respond to what I’ve posted.

I read Blink after Gladwell’s previous book, The Tipping Point — enjoyable, interesting, but a bit lightweight — and I thought much the same about Blink. It covers some interesting research, but not all of it supports Gladwell’s central thesis, that rapid, unconscious processing is usually better than conscious thought. There’s a long and critical review by the legal scholar Richard Posner at; Gladwell responds at

I’m not sure what books to recommend in this area, particularly those written for a general audience. The work on heuristics ghas been discussed by Dan Kahneman and his late colleague Amos Tversky in a number of articles (an early one being published in Science, if you have access to it – if not, e-mail me at danrbjones ‘at’ hotmail ‘dot’ com (obviously you need to put in the ‘@’ and ‘.’ – I’m trying to avoid spam) and I’ll mail you some articles).

10:11 pm GMT  
Blogger brainbark said...

I am not a religious person at all, but it occurs to me that people who pray before making a decision may actually be benefiting from the cognitive pausing phenomenon which you describe in this article. They are taking their mind off the decision for a while and thinking about something else (God). Later, they attribute all their good decision-making experience to their faith in God. This may have the effect of reinforcing religious belief.

10:42 pm GMT  

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