Does Irrelevant Information Play a Role in Judgment

Does Irrelevant Information Play a Role in Judgment? Boicho Kokinov (bkokinov@nbu.bg) 12 Penka Hristova (phristova@cogs.nbu.bg) 1 Georgi Petkov (gpetkov@cogs.nbu.bg) 1 Central and East European Center for Cognitive Science, Department of Cognitive Science and Psychology, New Bulgarian University, 21 Montevideo Street Sofia 1635, Bulgaria Institute of Mathematics and Informatics, Bulgarian Academy of Sciences, Acad. G. Bonchev Street, bl.8 Sofia 1113, Bulgaria Abstract This paper presents an unusual prediction made by the DUAL-based model of judgment JUDGEMAP and its verification. The model is shortly presented as well as the simulation data obtained with it. These data predict that people will use the information on an irrelevant dimension when judging another dimension. This prediction is then tested in a psychological experiment and confirmed. Introduction Suppose that you are judging how tall a person is. Do you expect that the color of his or her eyes will play a role in that process? Or suppose you are judging the quantity of oil in the bottle you are buying, do you expect that the font used on its label will have an effect? Finally, suppose you are judging the length of a given line segment. Do you expect that the color of the line will make a difference? Both our intuition and the theories of judgment would answer these questions negatively. Basically they would assume that when judging length we ignore all irrelevant features (including color) and only physical length plays a role. Of course, many other factors, like order of presentation and context, may play a role, but only the length of the lines will take part in the judgment. This paper is challenging this assumption of standard theories of judgment and is trying to answer the above seemingly stupid and self-evident questions and surprisingly to show that all features (including the irrelevant ones) do matter or more precisely they may matter under certain circumstances. Approaches to Judgment There are a number of theories of judgment and a few running models. Most of the theories originate from psychophysics and are mathematical in their nature; they do not describe the process of judgment, but only characterize the end result. Since we are interested in describing the process of judgment we will briefly outline only the main approaches proposed so far in that direction. Judgment as measuring similarity/dissimilarity with a standard. The classical ideal point approach proposed by Coombs (1964, Wedell & Pettibone, 1999) falls into this category. He believes individuals have their “ideal points” and therefore judging a stimulus can be described as comparing it to this standard and measuring the distance toward it. The Adaptation Level Theory (Helson, 1964) falls into the same category, however, here the standard (adaptation level) is changed depending on context. Finally, the Norm Theory (Kahneman & Miller, 1986) follows a similar approach, however, the standard here is called “norm” and what is more important is that this norm is constructed on the spot rather than retrieved from long-term memory. A comparison set is constructed in working memory consisting of known exemplars and its norm is computed. Thus all three theories can be described as relying on comparison of the target stimulus with a standard (Figure 1), but they differ in the degree to which they subscribe to the constructivist approach toward this standard. Comparison Set Target Standard Figure 1. Judgment as comparison with a standard. Judgment as classification task. Within this approach the comparison set is subdivided into subcategories each of them corresponding to a judgment label (or scale element) and the target stimulus is classified within one of these subcategories. The Range-Frequency Theory (Parduci, 1965, 1974) postulates the constraints which should be met by such category subdivision: the range of value variation within all subcategories should be about the same, and the number of examples in all subcategories should be about the same. The Theory of Criterion Setting (Treisman & Williams, 1984, Treisman, 1985) is a process model that explains how dynamically we change the boundaries of the subcategories. Finally, the ANCHOR model (Petrov &