Willpower: Rediscovering the Greatest Human Strength

For many years, willpower was out of fashion. In psychology, both Freudians and behaviourists were sceptical of the idea that we have conscious control, and the dominant view was that teaching self-esteem to children is a key determinant of their success in later life. That was challenged by a follow-up to some experiments that Walter Mischel ran in the 1960s. Mischel's original study involved leaving four-year-olds alone in a room with a single marshmallow, which they were free to eat whenever they wanted. But they were told that if they managed to wait until the experimenter's return, they would get an additional marshmallow. In a follow-up investigation decades later, Mischel found that those who had shown most willpower at age four were getting higher grades at university, even when differences in intelligence were controlled for.

Psychologist Roy Baumeister has spent much of his career investigating willpower and, together with journalist John Tierney, in this book he summarises his research for a popular audience and extracts practical advice.

Baumeister offers two main insights. First, you have one stock of willpower for all tasks, which gets depleted as you use it. Hungry students who were put in front of cookies and radishes but told not to eat the cookies then spent less time trying to solve impossible puzzles than students who had been allowed to eat from either bowl. Similarly, being given a task that required controlling their emotional responses affected students' performance on a subsequent task that required endurance.

Second, willpower is like a muscle and can be strengthened with exercise. Students who worked on their posture for two weeks, overriding their habitual slouching, showed improved scores on standard self-control tests. The more often they had forced themselves to sit up straight, the greater the improvement in self-control. (Although, given Baumeister's first insight, one wonders whether, during those two weeks, there was a deterioration of self-control in other activities, such as eating healthily, not over-spending and getting their work in on time. Baumeister and Tierney do not discuss how to balance exercising and depletion.)

Willpower is also supposed to be related to energy levels, so the authors advise getting a good night's sleep and eating properly. If you think that might explain the hungry students' poor performance in self-control tasks, you wouldn't be far off the mark. Baumeister and Tierney's general message is that if you improve your willpower in one area of your life, you will see improvements in other areas; however, they say dieting is the exception to the rule. We need glucose for self-control - but dieters who are controlling their food intake are denying themselves glucose and, therefore, weakening their willpower.

As well as dieting, the authors discuss other practical applications of willpower, such as giving up smoking and alcohol, controlling impulse spending, and child rearing. Despite their optimism about the possibility of improving one's willpower, much of the advice they give involves bypassing the will: forming habits, avoiding places of temptation or committing publicly to targets and then announcing whether or not you have met them.

They also strongly recommend constant monitoring, although that ignores one of the lessons from Mischel's experiment, where the children who were most successful at delaying gratification were those who distracted themselves from the treat, with one child even succeeding by going to sleep! The authors never really address the tension of whether we are better off working on improving our willpower or on distracting ourselves from temptation and thus obviating the need for willpower.

The book reads like a cross between a popular academic book and a self-help manual and, occasionally, like an advertisement for some of the commercially available software sold as an aid to self-control that Baumeister and Tierney clearly approve of - although they are honest enough to mention the lack of scientific trials of the efficacy of these programmes. It is long on anecdotes and sometimes short on evidence to back up speculative claims, especially where the authors stray out of the realms of psychology and into, for example, evolutionary explanations. Those who want more rigour and less product placement would be better off reading Baumeister's earlier book, Losing Control: How and Why People Fail at Self-Regulation. But this book is aimed at a wider audience and the authors have erred on the side of readability. It won't take much willpower to get to the end.