Extant models of the psychophysical function: a comparison.

Previous research has tested the efficacy of the deterministic-sensory model versus probabilistic-sensory-learning model for psychophysical relationships when cognitive factors were manipulated. The present study attempted to expand those findings by holding cognitive factors constant and varying a perceptual factor within a stimulus class. Subjects made magnitude estimations of skin-area contact for each of two sets of weights which varied identically in surface area but different in that one set also varied in accelerative force whereas the other did not. A power function was obtained only for that set which varied with respect to accelerative force, supporting the deterministic-sensory model. These results are consistent with those of electro-physiological studies which have related transducer activity to the dynamic component of a mechanical stimulus. It was suggested that better conceptualization of "cognitive" and "perceptual" factors is needed before further research in this area is undertaken.