Thinking, fast and slow

Thinking, fast and slow is a book by the eminent psychologist, Daniel Kahneman, that presents his view of how the mind works. It draws on recent developments in cognitive and social psychology, and includes as an appendix the "Prospect Theory" article "Judgement under uncertainty: heuristics and biases", for his part in which he was awarded the Nobel Prize in economics. The word fast in the title refers to "system 1" thinking, which operates automatically with little or no effort, and no sense of voluntary control. The word slow refers to "system 2", of mental activities that require concentration, effort and self-control. The book examines the evidence concerning circumstances under which system 1 supplies false information to system 2.

Part I. Two systems

Part I presents the basic elements of Daniel Kahnemann's two-systems approach to judgement and choice. Its purpose is to introduce a vocabulary for thinking about the mind. It describes experiments that demonstrate that both the cognitive effort and self-control of system 2 draw upon a limited resource of "mental energy", and actually involve the depletion of the blood system's glucose. It introduces the concept of "cognitive strain" as a response to effort and unmet demands - the absence of which is termed "cognitive ease". It reviews research which shows that cognitive ease is both a cause and a consequence of pleasant feelings (when in a good mood, people become more intuitive and more creative, but also less vigilant and more prone to logical errors). System 1 is seen as conserving mental energy while maintaining and updating a model of its possessor's personal world by forming associations with regularly-ocurring events and outcomes.