Dimension integration: Testing models without trade-offs

This paper tests a behavioral property called dimension integration. The test evaluates models, such as lexicographic semi-orders and the priority heuristic, which assume that a person uses only one dimension at a time. It provides a way to compare such models against those that assume a person combines information from different dimensions. The test allows one to test the hypothesis that different people use different lexicographic semi-orders with different threshold parameters. In addition, by use of a "true and error" model, it is possible to "correct" for unreliability of choice in order to estimate the proportions of participants who show different response patterns that can be classified as integrative or not integrative. An experiment with 260 participants was conducted in which people made choices between two-branch gambles. The aggregate results violate the priority heuristic and six lexicographic semi-orders. The data also refute the theory that people use a mixture of these lexicographic semi-orders. In addition, few individuals appear to show response patterns consistent with non-integrative models. Instead, they show that most individuals show patterns consistent with the hypothesis that they combine information between dimensions. (C) 2007 Elsevier Inc. All rights reserved.