A theory of psychological attributes and their measurability based on relational responding

We present a theory-based approach to psychological measurement based on the proposal that psychological variables are internal discriminative stimuli that are shaped by operant selection of relational responding. According to the formal requirements of representational measurement, we argue that a measurable psychological attribute emerges, if and only if relational responses are selected such that the resulting structure is homomorphic to a numerical structure such as the real numbers. We further embed the concept of emergent psychological attributes in the theory of operant selection, where selection is understood as a multilevel process that shapes behavior with regard to its expected fitness consequences. Thus, psychological attributes are context-dependent discriminative stimuli that are generated by the individual to enable the prediction of expected changes in evolutionary fitness, given a certain action is taken in that context. The theory has wide implications for the interpretation of psychological scales, as well as for the experimental study of measurement in psychology.