Über die Autorin bzw. den Autor

David Hardman has taught judgment and decision making at London Metropolitan University since 1998, where he is Principal Lecturer for Learning Development. He is co-editor of Thinking: Psychological Perspectives on Reasoning, Judgment, and Decision Making, and is an Associate Editor for the Journal of Economic Psychology.

Von der hinteren Coverseite

Judgment and Decision Making is a refreshingly accessible text that explores the wide variety of ways people make judgments. It examines assessments of probability, frequency and causation; as well as how decisions are rendered under conditions of risk and uncertainty. Topics covered include dynamic, everyday and group decision making; individual differences; and the nature of mind and brain in relation to judgment and decision making.

Offering up-to-date theoretical coverage, including perspectives from evolutionary psychology and neuroscience, this volume has everything a psychology student needs for BPS accreditation, whilst drawing out the practical applications for non-psychology students with plentiful examples from business, economics, sport, law and medicine. The latest addition to the BPS Textbooks in Psychology series, this thorough text provides a succinct, reader-friendly account of the field of judgment and decision making.

For more information and resources visit www.blackwellpublishing.com/judgment

Aus dem Klappentext

Judgment and Decision Making is a refreshingly accessible text that explores the wide variety of ways people make judgments. It examines assessments of probability, frequency and causation; as well as how decisions are rendered under conditions of risk and uncertainty. Topics covered include dynamic, everyday and group decision making; individual differences; and the nature of mind and brain in relation to judgment and decision making.

Offering up-to-date theoretical coverage, including perspectives from evolutionary psychology and neuroscience, this volume has everything a psychology student needs for BPS accreditation, whilst drawing out the practical applications for non-psychology students with plentiful examples from business, economics, sport, law and medicine. The latest addition to the BPS Textbooks in Psychology series, this thorough text provides a succinct, reader-friendly account of the field of judgment and decision making.

For more information and resources visit www.blackwellpublishing.com/judgment

Auszug. © Genehmigter Nachdruck. Alle Rechte vorbehalten.

Judgment and Decision Making

John Wiley & Sons

Chapter One

You've gotta make decisions. You've gotta keep making decisions, even if they're wrong decisions. You know ... if you don't make decisions, you're stuffed. (Joe Simpson explaining his epic escape from a mountaineering accident, in the documentary movie Touching the Void)

Our waking lives are largely devoted to making judgments and decisions of one sort or another, whether judging if it is safe to cross the road, deciding to quit your job and live the dream, or choosing what colour to paint your apartment. Although we often conflate the terms 'judgment' and 'decision' in everyday language, judgments are essentially evaluations or estimates whereas decisions indicate an intention to pursue a particular course of action. The decisions we make are, of course, informed by our judgment.

There are so many types of judgments and decisions that it might seem hard to believe that there could be any common processes involved in the ways we think about them. However, consider the following occurrences (perhaps you will even recognise these situations):

You have set your iPod to random shuffle, yet it seems to be playing certain artists more than others. Is there something wrong with your iPod's randomising device? In fact, occasional 'streaks' in outcomes are exactly what should be expected in random sequences.

You are having a lively discussion with someone who has a very strongly held belief on the subject. It seems to you that there is no amount of evidence that will change his mind.

There are a few purchases you have been thinking of making, but have held off from doing so on the grounds of expense. However, today you have just made a much larger expensive purchase, and shortly afterwards also made the smaller purchases you had been thinking about. Somehow, the large purchase seems to have made it easier to make the smaller purchases.

You are in a meeting at work. As time goes by you realise that a number of people are tending to dominate the conversation. Decisions are reached where some people hardly speak or don't speak at all. Do the decisions really represent the majority view? Why did the chair not try to ensure that all voices were heard?

The fact that such situations are common reflects something important about our basic psychology. Determining the nature of that psychology is the subject of much research and the subject of this book.

The examples above give a small flavour of this book's content, which includes assessments of uncertainty and probability, argumentation and the assessment of evidence, the role of value in decision making, and group decision making. Along the way I shall also look at other phenomena and processes, such as being wise after the event, judgments of causation and association, judgments about what might have been, decisions under risk and uncertainty, judgments and decisions over time, risk perception and risk taking, and factors influencing cooperation and coordination.

WHAT IS RATIONALITY?

One of the topics occasionally discussed by JDM researchers is the extent to which people can be considered 'rational'. Rationality is normally taken to mean adherence to some normative model, such as probability theory or decision theory. As the subsequent chapters will present many instances where people do not behave in accordance with normative models, I want to take a moment in this first chapter to ponder the nature of rationality.

Classical economists have tended to assume rationality as a given, hence the phrase rational economic man (or to use more contemporary non-sexist parlance, the rational actor). Although research conducted by psychologists has noted many discrepancies from rational theory, economists often respond by noting differences between the laboratory situation and the real world. In particular, the psychologists' participants tend to be naive about the situation and are asked to make one-off decisions, sometimes without incentives for accurate responses. Economists have argued that as people gain experience of a particular domain they learn accordingly and so behave in a more rational way. There is some evidence to this effect, but also there is considerable evidence of economically irrational behaviour even among those who are experienced in a particular domain (e.g. Haigh & List, 2005).

However, violations of rational norms by species with longer evolutionary histories than the human race (e.g. Shafir, 1994) are not generally taken to indicate that animals are somehow irrational. Rather, it is assumed that the mechanisms that contribute to evolutionary fitness may nonetheless not predict behaviour in certain specific instances.

An analogy is occasionally drawn with visual perception. Figure 1.1 shows the Mller-Lyer illusion. Compare the horizontal line in (a) with that in (b). Virtually everyone agrees that (b) looks longer than (a). In fact, both lines are exactly the same length, as you can easily verify by placing a ruler against each. The research literature on visual perception is full of such illusions. Although the Mller-Lyer illusion may seem somewhat artificial, illusions can occur even when we perceive the natural environment. For example, an illusion that most people are not aware of until it is drawn to their attention is the moon illusion. Compare the size of the full moon when it is just above the horizon to when it is high in the sky. The full moon just above the horizon appears much larger.

Despite the existence of such visual 'errors', there is no concern among vision researchers that there needs to be a mass correction of our visual systems in order to prevent such illusions. Clearly, our visual systems have evolved in such a way as to help us successfully navigate our environments. Likewise, the occasional error in making judgments and decisions may be a small price to pay for a cognitive system that is otherwise well adapted to facilitating our survival and reproduction. In fact, individuals who score higher on measures of intelligence are more susceptible to visual illusions (Jensen, 1998).

Such observations have led some researchers to question attributions of irrationality to humans. As Ayton (2000, p.667) put it (in the style of Irving Berlin): 'Birds do it, bees do it, even educated Ph.D.s do it; why not violate normative rules of rationality?' Nonetheless, the nature of the contemporary environment is very different from that within which our ancestors evolved, such that both the visual and the intellectual environment can pose problems where any errors can be costly. In Britain, and no doubt some other countries too, the exit roads from motorways often have a series of stripes painted across them. This is because people adapt to the speed that they travel at on the motorway and sometimes fail to slow to an appropriate speed when they leave the motorway. To motorway drivers exiting on a slip road, the stripes seem to whizz by really quickly, which...