Douglas H. Wedell

Distinguishing Among Models of Contextually Induced Preference Reversals

Previous research has demonstrated that adding a 3rd (decoy) alternative that is dominated by only 1 of the other 2 alternatives in a choice set increases the preference for the dominating alternative (J. Huber, Payne, & Puto, 1982; Tyszka, 1983). By manipulating decoys within subjects, significant preference reversals have been obtained. The processes of 3 classes of models can account for these reversals: (a) The decoy affects the weights assigned to different dimensions, (b) the decoy produces range-frequency effects on the dimensional values of the alternatives, and (c) the perception of dominance directly increases the attractiveness of the targeted alternative. The results of 3 experiments designed to test these models favored a direct effect of dominance. When a dominated decoy was added to a choice set, asymmetrical dominance was demonstrated to be a necessary and sufficient condition for producing the predicted preference reversals.

The Category Effect With Rating Scales: Number of Categories, Number of Stimuli, and Method of Presentation

Squares receive higher category ratings when the smaller sizes are presented more frequently than the larger sizes. This shift in the rating scale is greater when there are either fewer categories (the Category Effect) or more stimuli. Similar shifts were obtained whether the stimuli were presented successively for judgment or simultaneously. The Category Effect also occurred when subjects were not told how many categories to use until after the contextual stimuli had been presented. A simple range-frequency model describes most of the shifts in scale by variations in a single weighting parameter. However, these shifts are predicted by an elaborated model in which the number of representations of any stimulus in working memory is limited by a principle of consistent assignment of each stimulus to a single category. This elaborated model correctly predicts the disappearance of the Category Effect when contexts are manipulated by varying the spacing of stimulus values rather than by varying their relative frequencies.

Reference Price and Price Perceptions: A Comparison of Alternative Models

Reference price effects on consumer price perceptions are often explained by Helsons adaptation-level theory, in which the cognitive representation of reference price is the prototype of the relevant category. However, recent conceptualizations and empirical evidence suggest the possibility of an exemplar model, which may be specified using Volkmanns range theory or Parduccis range-frequency theory. In two experiments, these three contextual models of reference price effects are pitted against one another. Based on the MANOVA and model fitting, range-frequency theory accounted for reference price effects that the other theories could not, suggesting that consumers compare the target price against specific members of the category rather than the category prototype. A third experiment demonstrated that range and frequency effects are moderated by the stimulus presentation condition, suggesting that consumers place greater weight on extreme prices anchoring the range for internal reference prices than for external reference prices. Copyright 2001 by the University of Chicago.

VALIDITY ISSUES IN THE LIKERT AND THURSTONE APPROACHES TO ATTITUDE MEASUREMENT

This article highlights the theoretical differences between the Likert and Thurstone approaches to attitude measurement and demonstrates how such differences can lead to discrepant attitude estimates for individuals with the most extreme opinions. Both simulated data and real data on attitude toward abortion are used to demonstrate this discrepancy. The results suggest that attitude researchers should, at the very least, devote more attention to the empirical response characteristics of items on a Likert attitude questionnaire. At most, these results suggest that other methods, such as the Thurstone technique or one of its recently developed item response theory counterparts, should be used to derive attitude estimates from disagree-agree responses.

A formal analysis of ratings of physical attractiveness: Successive contrast and simultaneous assimilation

Photographs of faces were presented in a series, either singly or in pairs, for ratings of physical attractiveness. In Experiment 1, faces were presented singly, and both the range and relative frequencies of physical attractiveness (on baseline scaling) were manipulated experimentally. The same face elicited higher ratings when less attractive faces predominated in the experimental series, successive contrast. Increasing the number of available categories resulted in higher ratings but did not reduce the amount of successive contrast. Both range and skewing effects were in accordance with a range-frequency model that permits the subjective range to vary with number of categories. In Experiment 2, faces were presented in pairs. The same face now elicited lower ratings when presented simultaneously with a less attractive face, simultaneous assimilation. Successive contrast was again observed between pairs and was greater for 5- than for 101-point rating scales. A model that uses the judgments resulting from a range-frequency compromise as the stimulus values for integration within pairs provides the best account of how both contrast and assimilation occur within the same experimental session. Alternative interpretations of the observed contrast and assimilation were discussed.

Intrapersonal and social comparison determinants of happiness: a range-frequency analysis.

Examined whether intrapersonal comparisons and social comparisons operate in similar ways to determine ratings of happiness. Events were varied to create positively and negatively skewed distributions. The events in each distribution were ascribed to either a single person or a group of people; Ss rated how happy they would feel if they experienced specific events within the distribution. Ratings for both intrapersonal and social comparisons were fit well by Parduccis (1984) range-frequency theory. Individual events received higher ratings when presented within the positively skewed context. Overall happiness, as measured by both the mean of the happiness ratings as well as direct ratings, was highest for the negatively skewed distributions. The effects of skewing were more pronounced for intrapersonal comparisons, but ratings were more closely defined by the range of experimental stimuli for social comparisons.

Moderation of Preference Reversals in the Long Run

The evaluation of a monetary gamble requires consideration of two basic types of information: (a) the probabilities associated with winning and losing, and (b) the amounts to be won and lost. The well-documented phenomenon of preference reversals provides strong evidence that the processing of this information depends on how the evaluation is expressed (Goldstein & Einhorn, 1987; Grether & Plott, 1979; Lichtenstein & Slovic, 1971, 1973; Lindman, 1971; Slovic & Lichtenstein, 1983). When presented with two gambles close in expected value, many subjects choose a bet with a high probability of winning a modest amount of money (P-bet) over a bet with a low probability of winning a large amount (

Decoding the neural representation of affective states.

-bet), even though they place a higher minimum selling price on the

Testing boundary conditions for the conjunction fallacy: effects of response mode, conceptual focus, and problem type.

-bet. When confronted with the apparent inconsistency in their behavior and given the chance to change either of their responses, the majority of these subjects stand by their decisions (Slovic, 1986). In the typical preference reversal task, response modes may vary in two ways: (a) subjects either make a choice between two lotteries or make a judgment of each separately, and (b) the focus is either on the monetary value of the gamble or on its attractiveness. Goldstein and Einhorn (1987) manipulated these two factors independently and demonstrated preference reversals associated with each. Although recent research (Tversky, Sattath, & Slovic, 1988) has demonstrated preference reversals for nonprobabilistic stimuli, the vast majority of preference reversal studies have used gambles as stimuli. In this article, we explore the possibility that these preference reversals are largely due to the way in which people evaluate probabilities for unique, one-shot events. Two experiments test this hypothesis by varying the number of times a gamble

Reducing the Dependence of Clinical Judgment on the Immediate Context: Effects of Number of Categories and Type of Anchors

Brain activity was monitored while participants viewed picture sets that reflected high or low levels of arousal and positive, neutral, or negative valence. Pictures within a set were presented rapidly in an incidental viewing task while fMRI data were collected. The primary purpose of the study was to determine if multi-voxel pattern analysis could be used within and between participants to predict valence, arousal and combined affective states elicited by pictures based on distributed patterns of whole brain activity. A secondary purpose was to determine if distributed patterns of whole brain activity can be used to derive a lower dimensional representation of affective states consistent with behavioral data. Results demonstrated above chance prediction of valence, arousal and affective states that was robust across a wide range of number of voxels used in prediction. Additionally, individual differences multidimensional scaling based on fMRI data clearly separated valence and arousal levels and was consistent with a circumplex model of affective states.