A Critique of S. S. Stevens' “New Psychophysics”

S. S. Stevens' “New Psychophysics” is examined in terms of classical psychophysics and recent experiments. Distinctions between metathetic and prothetic continua, and between category and ratio scales are considered inappropriate. Conclusions drawn from cross-modality matching are questioned. We suggest that central nervous system processes determine the quantitative nature of psychophysical responses, as described by the physical correlate theory, rather than the operating characteristics of sensory transducers.