On the Misapplication of Cybernetics to Sensory Neurons: Norwich’s Informational Entropy Theory of Perception Has Not Derived Stevens’ Law for Taste

Norwich’s Entropy Theory of Perception reveals a startling conclusion: that Stevens’ Law with an Index of 1, a power function stating direct proportionality between perceived taste intensity and stimulus concentration, arises purely from theory. Norwich’s theorizing starts with extraordinary hypotheses. First, “multiple, parallel receptor-neuron units” without collaterals “carry essentially the same message to the brain”, i.e. the rate-level curves are identical. Second, sensation is proportional to firing rate. Third, firing rate is proportional to the taste receptor’s “resolvable uncertainty”. Fourth, the “resolvable uncertainty” is obtained from Shannon’s Information Theory. Finally, “resolvable uncertainty” also depends upon the microscopic thermodynamic density fluctuation of the tasted solute. Norwich proves that density fluctuation is density variance, which is proportional to solute concentration, all based on the theory of fluctuations in fluid composition in Tolman’s “The Principles of Statistical Mechanics”. Altogether, perceived taste intensity is theoretically proportional to solute concentration. Now, a universal rule for taste, one independent of solute identity, physiological differences, and psychophysical task, is well-deserving of scrutiny. Norwich’s crucial step, the derivation of density variance, was meticulously reconstructed. It transpires that the appropriate fluctuation is Tolman’s mean-square fractional density fluctuation, not the density variance, altogether giving a “Stevens Index” of -1 rather than 1. Thus, Norwich’s Entropy Theory of Perception has not derived Stevens’ Law for taste. Norwich’s mistake reveals the dangers of implying psychophysical laws from information theory and stimulus physics without accounting for sensory transduction.