Hedonic integration: Test of a linear model

A simple adding model was tested for the integration of the hedonic component of taste stimuli. Subjects tasted mixtures of quinine sulfate and apple juice and rated the pleasantness of the composite taste, The rating data showed significant nonadditivity, which could reflect failure of the model itself or merely a nonlinear response output function. Since the rating data could be transformed to additivity, justification for such transformation was sought through a second task based on the logic of two-stage integration. In this task, subjects rated the difference between taste mixtures. The subtracting model underlying this judgment provided functional scale values for the taste mixtures on validated interval scales. These functional scale values were consistent with the predictions of the simple adding model, and thus justified the transformation of the single rating data to additivity. The application of functional measurement to obtain the psychophysical functions of the two taste components is also illustrated.