Why additive utility models fail as descriptions of choice behavior

Abstract

This experiment sought to determine whether previously found metric violations of additive expectancy-value models C.F. J. C. Shanteau, Journal of Experimental Psychology, 1974 , 103, 680–691; J. G. Lynch and J. L. Cohen, Journal of Personality and Social Psychology, 1978 , 36, 1138–1151) were attributable to the inappropriateness of these models or to nonlinearities in the relationship between numerical ratings and underlying psychological impressions. Undergraduate participants performed two tasks employing the same experimental stimuli. In the first task, they rated the subjective values of hypothetical bets, judged separately and in combination. In the second task, they made pairwise comparisons of the same bets in terms of preference. The use of the same experimental stimuli in both tasks allowed a test of alternative models of utility judgment through application of the criterion of scale convergence ( M. H. Birnbaum & C. T. Veit, Perception and Psychophysics, 1974 , 15, 7–15). Results suggested that the additive expectancy-value model of judgments of the utilities of combinations of outcomes should be replaced by a weighted averaging rule in which the weight given to the value of each outcome in the averaging process is greater when this value is negative and extreme than when it is neutral.