Perceived intensity of the taste of sugar mixtures and acid mixtures

The taste intensity of fructose and sucrose mixtures, and of HCl and citric acid mixtures, were determined by magnitude estimation. The sugar mixtures showed synergy at low levels and suppression of perceived intensities at higher ones. The acid mixtures showed additivity except at higher concentrations where suppression was found. These findings were inconsistent with additive models which represent total intensity as a sum of the subjective intensities of its components, but are consistent with Bartoshuk's model which associates synergy, additivity or suppression with the forms of the functions characterizing the psychophysical relations for the components of the mixture, if it is assumed that the functions are not power functions. A model by Beidler was also found to provide an excellent description of the psychophysical relation for mixture data, if it is assumed that a non-linear response transformation is introduced in judgement.