CeDEx Seminar - Michele Bernasconi (Ca' Foscari University of Venice)

Subjective measurement on ratio scales: from perceptual continua to utility

Abstract

A fundamental question in the behavioral sciences concerns the ability of individuals to evaluate quantities. We focus on ratio evaluations in which individuals do not measure absolute quantities, but relative ones. According to psychophysics Stanley Stevens (1946, 1951, 1975), subjective ratio estimations should be treated as any other form of scientific measurement and acknowledged as exhibiting the usual standard of scientific reliability. It is well-known that outside psychophysics, Stevens' approach has been routinely criticized because of lack of rigor. More recently, however, research in mathematical psychology has clarified the conditions and has given the set of axioms that justify subjective ratio scale measurement (Luce 2002, 2004, 2008, Narens 1996, 2002, 2006). Two axioms are in particular essential to obtain meaningful representation measure from subjects’ ratio scaling: multiplicativity and commutativity. The representations are sometimes called separable representations. We review the literature, theoretical and experimental, testing the axioms of multiplicativity and commutativity in the context of several perceptual domains. And we investigate experimentally whether the axioms of separable representations can be extended to measure the utility of money on a subjective ratio scale.