Studies on the perception of taste: do primaries exist?

The idea that there are four primary tastes is basic to almost all research in gustation. Although this concept guides the formulation and interpretation of studies of taste psychophysics, as well as studies of taste stimuli, receptors, and neural organization, there is a surprising absence of studies designed to determine if this quadripartite view of taste is correct. The present group of three studies is designed to ask this question on a psychophysical level, comparing the taste data with combinations of tones, which appear to remain separate; subjects are asked: (a) whether tastes and tones--including mixtures--are perceived as singular or more-than-one, (b) whether increasing the number of components in a mixture (tastes or tones) results in increases in the perceived complexity, and (c) whether stimuli (tastes or tones) remain identifiable in mixtures with other stimuli. In all three experiments, it appears that the individual tones remained distinct and unaltered in combinations. Taste stimuli combined very differently from tones, in ways that suggested that the original components lost their identity, and sensations other than those in the original components (e.g., "primary tastes") were synthesized. From this it follows that taste is composed of many sensations, not just the "primary four."