Subjective intensity: Behavioral laws, numerical representations, and behavioral predictions in Luce's model of global psychophysics

This article summarizes the theoretical work of R. Duncan Luce towards a unified psychophysical theory of the percepts of all intensive domains. Also summarized are the empirical evaluations of it carried out to date. The theory is a comprehensive application of axiomatic measurement theory. The approach, mimicking classical static physics, is based on behavioral-and testable-axiomatic invariances that imply a numerical representation (a measurement scale) and its properties. The empirical work involves interpreting the primitives of the theory in a domain and then evaluating the behavioral properties. If supported, the representations follow from the properties, forming a descriptive model for that domain. The theory differs in some details depending on whether percepts involve an interplay between two sensors (2-D) (e.g., two eyes/ears) or just one (1-D). The theory has been substantially evaluated and supported in the 2-D domains of loudness, brightness, and perceived contrast. Empirical work for 1-D domains is less complete. Novel inferences and predictions flow from the theory and several of these, along with empirical work, are summarized.