# Order Effects in Probabilistic Reasoning – Potentialities and Limits of Modeling Methods

- Franziska Bocklisch,
*Chemnitz University of Technology*
- Josef F. Krems,
*Chemnitz University of Technology*
- Katja Mehlhorn,
*Chemnitz University of Technology*

## Abstract

A well-known phenomenon in sequential reasoning processes is that
the order of information (congruent/incongruent with certain hypotheses)
influences the assignment of probabilities to hypotheses and in turn, judgments
of them. For instance, order effects are known to have severe consequences in
medical diagnosis and tactical military decision making (Chapman et al., 1996;
Zhang et al., 1998). Hogarth and Einhorn (1992) Belief-Adjustment Model (BAM)
describes cognitive mechanisms that result in different types of order effects
and precise predictions of probabilities can be derived. In the present study BAM
model was contrasted with a Bayes net (Pearl, 1988) model that predicts competing
probabilities for the experiment in which participants estimated the
probabilities of hypotheses during the reasoning process. Results show, that both
models predict different parts of the same data. Overall, the fit is not
sufficient and we conclude that order effects can be explained by an interaction
of several cognitive processes.

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