Dawes, Robyn

views updated

Dawes, Robyn 1936-


Robyn Mason Dawes is the Charles J. Queenan Professor and former chair at the department of Social and Decision Sciences at Carnegie Mellon University. He received his PhD in mathematical psychology from the University of Michigan in 1963. Dawess work on human judgment and decision-making has influenced theory, research, and practice in diverse areas of psychology, including cognition, social behavior, and clinical assessment.

Inspired by Paul Meehls demonstration that simple statistical models outperform clinical judgment, Dawes showed that improper (i.e., unit-weight or even random-weight) regression models perform better than individual clinicians do as long as each predictor variable has some validity. Application of a linear combination formula yields reliable predictions, assuming the models user knows how to add. In contrast, intuitive judgments remain vulnerable to random errors and systematic biases. Although statistical prediction models promise to make judgments about people easy, efficient, and accountable, many practitioners continue to reject them, a resistance that has led Dawes to explore human irrationality more broadly.

Dawess analysis of human (ir)rationality is informed by Daniel Kahneman and Amos Tverskys work on heuristics and biases. Although judgmental heuristics often yield correct predictions, they guarantee that some contradictions will also occur. One such contradiction involves a structural availability bias that seduces people to make frequency judgments about events they could not have observed. For example, clinical psychologists sometimes claim that certain problem behaviors never stop on their own without therapy, when they have no information about behavior outside of the therapeutic context.

Dawess focus on internal consistency as a criterion of rationality is narrower, but also more precise than competing definitions of rationality in terms of evolutionary or ecological adaptiveness. Dawes identifies the failure to make appropriate comparative judgments as a hallmark of irrationality. Often, people seek to understand surprising or distressing events retrospectively. For example, an airplane crash tends to stimulate reviews of other crashes in hopes that a cause can be found. To reach a valid conclusion, however, flights ending in crashes need to be compared with successful flights. The former analysis can only reveal what the flights of interest have in common, but it obscures crucial information about whether the rate of these common features is actually higher (or perhaps lower) than their rate in uneventful flights.

In Bayesian statistics, comparisons are expressed as likelihood ratios. For example, the probability of a plane crash given fog in the landing area is divided by the probability of a crash given the absence of fog. When multiplied with an events base rate, the likelihood ratio yields coherent predictions. Although base rate neglect is also a facet of irrationality, Dawes is mainly concerned with the human tendency to neglect the ratios denominator.

Nonetheless, Dawes is optimistic about peoples capacity to think rationally. His analogy is learning how to swim. Novices try to keep their heads above water at all times, which makes drowning more likely. Once they learn to keep their faces in the water, and to come up for air only intermittently, they get it.

Coherent judgments reduce the number of prediction errors, but they do not guarantee that outcomes will be desirable. Evil can be rational and banal, as a reading of the autobiography of Rudolf Höss, commandant at Auschwitz, suggests. If the premises are loathsome, rational deductions are sure to be loathsome too. After rejecting the classic view that irrationality stems necessarily from the intrusion of emotions, Dawes concludes, like Bertrand Russell had done before him, that sensitivity to affect can benefit social judgment.

The inability of pure rationality to provide socially desirable outcomes is most evident in social dilemmas. Here, freedom-from-contradiction rationality dictates that each individual defect from the group (e.g., by choosing to pollute) because no matter what others do, the individual is better off. Garrett Hardin famously derided appeals to conscience as a way of increasing social cooperation. Dawes and colleagues, however, showed that allowing people to form a sense of a shared group identity makes them more likely to exchange and honor promises of cooperation. However, identity-based cooperation is still irrational. In a group of promise-makers, an individual who believes that others will be true to their word may be even more tempted to defect.

Dawess rigorous analyses have some surprising implications. He argues, for example, that when proper comparisons cannot be made, the only rational conclusion is to conclude nothing. In research, randomized trials provide the only rational basis for causal conclusions, which means that causal inferences from post-hoc statistical controls have no defensible basis, and that it would therefore be better not to conduct such studies. Like researchers, ordinary individuals must find out when to give up. People who fail to acknowledge uncertainties that cannot be overcome, end up overpredicting their future and persisting in costly behaviors that have no demonstrable benefits.

The impact of Dawess work within psychology and across disciplinary boundaries is noteworthy because Dawes did not establish an academic school of thought. His legacy is a firm rejection of academic tribalism and grand theorizing. Instead, he champions rigorous research, careful analysis, and acceptance of the limits of that which can be known.

SEE ALSO Bayesian Statistics; Cognition; Rationality; Social Cognition; Social Cognitive Map; Social Psychology


Dawes, Robyn. 1988. Rational Choice in an Uncertain World: The Psychology of Judgment and Decision Making. San Diego, CA: Harcourt, Brace, Jovanovich.

Dawes, Robyn. 1994. House of Cards: Psychology and Psychotherapy Based on Myth. New York: Free Press.

Dawes, Robyn. 2001. Everyday Irrationality: How Pseudo-Scientists, Lunatics, and the Rest of Us Systematically Fail to Think Rationally. Boulder, CO: Westview.

Dawes, Robyn, with Clyde H. Coombs and Amos Tversky. 1970. Mathematical Psychology: An Elementary Introduction. Englewood Cliffs, NJ: Prentice Hall.

Joachim I. Krueger