Berndt Brehmer

Dynamic decision making: human control of complex systems

This paper reviews research on dynamic decision making, i.e., decision making under conditions which require a series of decisions, where the decisions are not independent, where the state of the world changes, both autonomously and as a consequence of the decision makers actions, and where the decisions have to be made in real time. It is difficult to find useful normative theories for these kinds of decisions, and research thus has to focus on descriptive issues. A general approach, based on control theory, is proposed as a means to organize research in the area. An experimental paradigm for the study of dynamic decision making, that of computer simulated microworlds, is discussed, and two approaches using this paradigm are described: the individual differences approach, typical of German work in the tradition of research on complex problem solving, and the experimental approach. In studies following the former approach, the behaviour of groups differing in performance is compared, either with respect to strategies or with respect to performance on psychological tests. The results show that there are wide interindividual differences in performance, but no stable correlations between performance in microworlds and scores on traditional psychological tests have been found. Experimental research studying the effects of system characteristics, such as complexity and feedback delays, on dynamic decision making has shown that decision performance in dynamic tasks is strongly affected by feedback delays and whether or not the decisions have side effects. Although neither approach has led to any well-developed theory of dynamic decision making so far, the results nevertheless indicate that we are now able to produce highly reliable experimental results in the laboratory, results that agree with those found in field studies of dynamic decision making. This shows that an important first step towards a better understanding of these phenomena has been taken.

In one word: Not from experience ☆

Abstract Studies on clinical inference show that people do not always improve their judgments with experience. This paper argues that the expectation that they will improve is mistaken and founded on an incorrect conception of the nature of experience. Changing this conception towards a more adequate one along the lines suggested by Popper (1963) leads to a far more pessimistic view about peoples ability to learn from experience, a view that is in closer corrrespondence with the facts from studies on clinical judgement. The paper also reviews results from psychological studies concerned with peoples ability to learn from experience in probabilistic situations. These studies show that people have a number of biases which prevent them from using the information which experience provides. Examples of such biases are the tendency to use confirmatory evidence, assumptions about causality, and disregard of negative information. The paper argues that these biases can be understood in terms of the kind of information that people actually have to use when learning from experience outside the laboratory.

Experiments with Computer-Simulated Microworlds: Escaping Both the Narrow Straits of the Laboratory and the Deep Blue Sea of the Field Study.

Abstract This article discusses experimental work with computer-simulated microworlds as a means for overcoming the tension between laboratory research and field research in psychology. Research with such microworlds involves the study of how subjects interact with complex computer simulations of real systems, such as a small town or a forest fire. This kind of research has followed three different lines: (a) the individual differences approach, (b) the case study approach, and (c) the experimental approach. In the former approach, large groups of subjects interact with a given system, and the differences in their behavior is noted and related to various measures of abilities and personality. In the second, the behavior of individual subjects is analyzed in great detail to find typical and atypical behavior in an attempt to generate hypotheses. In the third approach, the effects of various system characteristics on behavior are studied at the group level. Experiments with such microworlds differ in important respects from traditional psychological experiments, and come closer to the situation studied in fieldwork.

Chapter 3 What Have we Learned about Human Judgment from Thirty Years of Policy Capturing

Publisher Summary The fundamental problems for research in social judgment theory (SJT) are to understand and improve achievement and agreement. Descriptions of judgment must contribute to the solution of these problems. This chapter explores the learning from studies of policy capturing about those factors that affect achievement and agreement. The typical policy capturing study does not vary any characteristics of the task, but presents the same task in the same form to all subjects in the study. Policy capturing is used as a general term for studies that analyze judgments made on the basis of multidimensional stimuli by means of a linear model. Policy capturing implies that the subjects have some policy that can be captured, and that the conditions under which the subjects are asked to make their judgments are related to the conditions under which they normally do so. A task may be nonrepresentative in at least two different ways—namely, (1) with respect to the format of the information provided to the subjects, and (2) with respect to the formal statistical properties of the task.

Pathoses associated with mandibular third molars subjected to removal

OBJECTIVES To measure the prevalence of disease of mandibular third molars referred for removal and to estimate the risk for development of pathoses for two cues. STUDY DESIGN A prospective cohort study on molars subjected to removal was performed. The prevalence of different diseases and the patients age, angular position, and degree of impaction of the molars were registered. Odds ratio for molars with different positions and impaction states were estimated. RESULTS Pericoronitis was found in 64% of cases, caries in the third molar in 31%, periodontitis in association with 8%, caries in the second molar in 5%, and root resorption of the second molar with 1% of the molars with pathoses. Odds ratio was highest for distoangular molars (5.8) and for molars partially covered by soft tissue (6.7). CONCLUSIONS The odds ratio is about 22 and 34 times higher for molars partially covered by soft tissue than for molars completely covered by soft or bone tissue. For distoangular molars the odds ratio is 5 to 12 times higher than for molars in other positions.

The psychology of linear judgement models

Abstract The ordinary policy capturing paradigm that focuses on cue-judgement relations is too limited to serve as a basis for a theoretical understanding of human judgement. To get on, we need a Brunswikian approach with a representation of both the task and the judge. Three stable results from studies with linear models are discussed from that perspective. Following Einhorn et al. (1979), the result that linear models usually fit judgement data well is explained by reference to the fact that linear models capture an essential feature of human judgement, viz., vicarious functioning. For the result that judges are inconsistent and that inconsistency varies with the predictability of the judgement task, the theory of quasi-rationality proposed by Hammond and Brehmer (1973) is invoked. Finally, it is argued that the wide interindividual differences in policies usually found show that the level of analysis is inappropriate. A given level of achievement can be reached by many different combinations of weights, and we should not be surprised to find wide interindividual differences at the policy level. We must search for stability at the level of achievement and those aspects that affect achievement, rather than at the level of cue utilisation coefficients.

Subjects’ ability to use functional rules

Ss’ ability to assign numbers to lines according to four different rules—positive linear (PL), negative linear (NL), U-shaped (U), and inversely U-shaped (ITJ)—was studied. The Ss were found to be more skilled in using the PL rule than all other rules and more skilled in using the NL rule than the two nonlinear rules. Implications of these results for functional and correlational learning, as well as for psychophysics, are discussed.

Use of experts in complex decision making: A paradigm for the study of staff work

Abstract The paper presents a general experimental paradigm for the study of staff decision making based on the basic principles of social judgment theory. In an illustrative experiment, the paradigm is used to study one of the fundamental problems of staff decision making, that of judging what weight the inputs from different staff members should have in the final decision. The results suggest that judging these weights is a difficult task, even under the simplified conditions of the experiment.

Asymptomatic mandibular third molars: Oral Surgeons' judgment of the need for extraction☆

Ten oral surgeons were asked to judge the need for extraction of asymptomatic mandibular third molars. Thirty-six mandibular third molars with equal distribution of angular position, impaction status, and patients sex and age were selected. To estimate the consistency of judgment, the 36 cases were duplicated so that, in all, 72 cases were judged. The judgment of the oral surgeons was compared with that of 30 general dental practitioners (GDPs). The number of mandibular third molars the oral surgeons proposed to extract varied from 3 to 21 of 36 teeth. The mean number of molars proposed for extraction was 12 for the oral surgeons and 13 for the GDPs. There was no third molar that all the observers in the two groups agreed should be extracted. About three times as many observers in both groups proposed extraction of molars partially covered by soft tissue. The oral surgeons were unanimous in their judgment not to extract 11 molars, and the GDPs were also unanimous in judgment not to extract two of these. The mean intraobserver agreement within the two groups was comparable, 94% for the oral surgeons and 92% for the GDPs. We conclude that there is a great variation among oral surgeons in their judgment on the need for removal of asymptomatic mandibular third molars. A similar variation in judgment also was observed among GDPs.

Chapter 1 The Development of Social Judgment Theory

Publisher Summary This chapter introduces social judgment theory (SJT). It focuses upon the conceptual structure of the framework and traces its development from the roots in Brunswiks probabilistic functionalism to its present form. SJT is a general framework for the study of human judgment. It is a metatheory which gives direction to research on judgment. SJT is the result of a systematic application of Brunswiks probabilistic functionalism to the problem of human judgment in social situations. Brunswiks theory of perception is also called “cue theory.”According to such a theory, a person does not have access to any direct information about the objects in the environment. Instead, perception is seen as an indirect process, mediated by a set of proximal cues. In accordance with this view, SJT defines judgment as a process which involves the integration of information from a set of cues into a judgment about some distal state of affairs. The lens model illustrates an important methodological principle in SJT: the Principle of Parallel Concepts. This principle states that the cognitive system and the task system must be described in terms of the same kinds of concepts.