A General Equi-Distance Scale of the Four Qualities of Taste

An equi-distance scale of intensity for the four primary qualities of taste has been constructed. Direct assessments of difference in intensity were made of two solutions presented in pairs; pairs of solutions of different concentration of the same substance or pairs of solutions of different substances. With a special procedure of analysis, it has been shown that a single common core component is definable throughout eight Ss' individual criteria for the comparative judgments and the scale has been defined on the core component. The Ss consisted of 4 specialists of taste-testing and 4 laymen. Intensity of taste on this scale is logarithmic functions of concentration with the slopes almost the same for the four qualities. The present scale based on difference judgments is related to the gustscale based on ratio judgments in the manner as expected from the general trend in prothetic continua.