Some Fundamental Issues in Psychophysical Scaling
In this final chapter, a few controversial issues in scaling that have led to advances in psychophysical methodology and theory are considered. Some of the questions raised in this chapter have yet to be answered. For example, is the power law an accurate description of the relationship between stimulus and sensation and, if so, is the physiological correlate of the power law to be found in the rules by which sensory receptors transduce environmental stimulation into neural activity? What is the explanation for the finding that different scaling procedures produce different psychological scales? What are the best ways to scale psychological experiences that vary simultaneously along several psychological dimensions at the same time? What are the integrating principles in psychophysics that make fundamental connections between the diverse experimental findings and theories of psychophysics?
There is little doubt that the power function represents the best description of the relationship between an observer's magnitude estimation judgments and stimulus intensity. However, there is more than one possible interpretation of this finding.
One interpretation of the power law is that it reflects the operation of sensory mechanisms as they transduce stimulus energy into neural activity. S. S. Stevens ( 1970, 1971b) has proposed that, because the neural output of