Similarity between stimuli: An experimental test of the Luce and Restle choice models

Abstract

A set of choice alternatives was constructed to test Restle's (1961) hypothesis about the role of similarity between alternatives in choice behavior. The set contained names of three political figures, three actresses, and three athletes, with the intention of producing considerable similarity within subsets and minimal similarity between subsets. Subjects were asked to select the individual with whom they would prefer to spend an hour of conversation. Paired-comparison choice data from 234 college subjects were consistent with expectations based on Restle's model, and disconfirmed Luce's (1959) stronger model which does not take similarity into account. Measurements of response strength for choosing the individual alternatives, and of perceived similarity between pairs of alternatives can be obtained using Restle's model, and the present test provides evidence for the validity of such measurements. Finally, Restle's model is shown to be indistinguishable from a modification of Thurstone's (1927) Case V, where the assumption of zero correlation is relaxed to permit nonnegative correlations between pairs of discriminal dispersions.