Gerd Gigerenzer

Gut Feelings: The Intelligence of the Unconscious

To make a decision we should carefully consider all aspects of the question before coming to a conclusion, shouldn't we? Not according to Gerd Gigerenzer. In this book, based on experiments he has conducted at the Max Planck institute for Human Development, he argues that the quick, off the cuff decision will often be better than that reached by long deliberation.

Where does our intuition come from?

The book is in two parts, and the first,'Unconscious intelligence', is primarily concerned with where our intuition comes from. Gigerenzer looks at the assumptions that we make in assessing a scene. In a picture we expect the light will come from above, and this can lead to optical illusions. We automatically infer something about a person's thoughts from the direction of their eyes. The book discusses how such instinctive knowledge would have evolved, and what the benefits of using it to make quick decisions. Of course in the world of 'eat or be eaten' there usually isn't time for deliberation, but there is also the point that as relationships between people became more complex it wouldn't do to be seen as being too calculating. One experiment which is discussed in this part is that of a rat which has two different places in which to look for food. Food is present in one place 80% of the time and 20% of the time in the other. Interestingly the rat visits these two places in the same proportion, rather than always going for the most likely option. Illogical? Not if you think in terms of a group of rats, where some choosing the 20% option means that a potential food source doesn't go to waste. The last chapter of this part, 'Why good intuitions shouldn't be logical' expands on this idea that the seemingly most logical option isn't always the best. It makes a good antidote to those books which berate us for not being able to think logically. Gigerenzer shows that, if you get away from the artificial examples in such books, our intuitive reasoning is often the best.

Why we should trust our intuitions

The second part of the book 'Gut feelings in action' gives some real world examples of the benefits of using our intution. As part of an experiment, German students were given questions asking which of two cities was the larger. A set of easy questions used German cities, while American cities were used in a more difficult set. Unfortunately the students got better scores with the 'difficult' questions than with the 'easy' ones. realised that in the 'difficult' case the students would often only recognise the name of one of the cities, which would likely be the largest. Hence . Later chapters describe how making decisions based on a single criterion is likely to be better than a detailed weighing of all of the information available. Thus the complex issues of politics are reduced to the single left-right dimension. Even when more than one factor has to be taken into account, the best approach will probably be to list the factors in order of importance, go down the list until a deciding factor is found, and stop there. One chapter deals with the applications of these ideas to healthcare. Doctors who had to judge whether to send patients to the intensive care ward or not had a calculator into which they were supposed to enter the relevant factors, and it would then provide an answer. It worked, but only if the doctors actually used it, and its complexity meant that they were reluctant to do so. Introducing a much simpler 'fast and frugal tree', in which decisions were made on the basis of one criterion at a time, worked just as well and was much simpler to implement.

Moral and Social behaviour

The last two chapters look at how our intuitions relate to our moral beliefs and social behaviour. There is an example of a police batallion from Nazi Germany which were given the task of massacring Jews from a Polish village. Despite the fact their commander gave each of them the option of not taking part, and that most of them found this a horrible task, the majority still went through with it - the pressure to conform is that strong. Gigerenzer shows how moral decisions are generally made on the basis of one overriding reason, and how rationally calculating the influence of several reasons seems morally dubious. The final chapter examines how our social norms can arise - imitating the 'done thing' is often the safest course of action. But such norms can also quickly be destroyed. An example given is the fall of the Berlin Wall, in which a few minor changes to regulations were misinterpreted and led to widespread belief that the border was going to be opened up. The resulting pressure on those in charge meant that this belief was then translated into fact.


A few of the reviews I've seen of this book criticise it on the basis that it spins out a few ideas into a whole book. I would agree that the 'size of two cities' experiment plays a prominent part, and final chapter and much of the previous one are only loosely related to the rest of the book. For these reasons I'd judge that it is unlikely to win the 2008 Royal Society Science Book Prize. But it's certainly worth reading, and I would say that this is the best of the books I've read on this sort of topic (of which there seems to be quite a few recently)Gut Feelings is amusing and easy to read, but is also useful as a guide for those wishing to improve their decision making.

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