Learning of probabilistic inference tasks : effects of uncertainty and function form

Sammanfattning: This thesis is concerned with the problem of how people learn to use uncer­tain information for making judgments. The general framework for the thesis is Social Judgment Theory (SJT). First the S3T paradigm, and some research conducted within the paradigm, is briefly described, and a series of four empirical studies is summarized. The studies are concerned with two factors that have been found to have great effect on subjects achievement in cue probability learning (CPL) tasks: task predictability, and the form of the function relating cue and criterion. The effects of these two factors were studied in experiments employing cue-probability learning tasks. The studies concerned with task predictability addressed the following questions (a) Do subjects understand the probabilistic nature of CPL-tasks? (b) Are subjects able to detect that a random task is, in fact, random, a study undertaken to test an aspect of Seligmans "theory of helplessness". This was also an attempt to bring emotional factors more in foeus.(c) Do subjects use data from the task only to test hypotheses, or do they use data also to construct hypotheses?The results showed that (a) subjects do not seem to be able to cope with probabilistic tasks in an optimal statistical manner. Instead they seem to use a deterministic approach to the tasks, because they do not understand the probabilistic nature of the task, (b) Task predictability affecs subjects mood, but not in the way predicted by Seligman, (c) Subjects seem to use data frorn the task only to test their hypotheses. The results thus supported the hypo­theses sampling model for the learning of CPL-tasks.As for the factor of function form, the following questions were addressed, (a) What hypotheses about relations between variables do subjects have? (b) Is the difficulties subjects have in learning complex rules in CPL-tasks due to a low availability of hypotheses about complex rules? The results showed that, (a) the hypothesis hierarchy as revealed in the present experiments was in general agreement with earlier results. However, few nonlinear hypotheses were observed, and other rules than functional rules were observed, (b) The difficulties subjects have to learn complex rules in CPL-tasks do not seem to be caused by low availability of rules.Finally, some suggestions are given for how the SJT-paradigm should be deve­loped. Specifically, it is suggested that the effects of emotional factors should be given more attention, and that the paradigm should be turned into a more general hypothesis testing model