Odor-taste mixtures.
A solution with both an odor and a taste may be considered to be a mixture that involves two sensory modalities. Estimates of the intensity of such mixtures appear to be additive. If the overall intensity of each of the unmixed components is compared with the overall intensity of the mixture, the additivity approaches 100%. If the intensities of the smell and taste of the unmixed components are compared with the overall intensity of the mixture, the additivity is less than 100%. Thus, the specific question that is given to the subjects influences the magnitude of the estimations. This suggests that the additive process involves a central (cognitive) mechanism. Considering that the perception of complex flavors also involves sensory information of touch, temperature, and possibly vision and hearing, a central interpretation seems appropriate. The influences of smell on the perception of taste also appear to involve a cognitive mechanism. These smell-taste confusions appear to be stimulus specific and are usually resolved in favor of taste. This may be true because the sensations of pressure, movement, and resistance are usually localized in the mouth. These accompanying sensations then suggest that the taste organs are active in determining the result even when no true taste is present. The influences of taste on the perception of smell are most pronounced when the tastant contains an odor. This suggests that the effect may be peripheral. That is, odorant molecules may be moving from the pharynx, through the posterior nares, to the olfactory receptors. If this interpretation is correct, the influences of taste on smell may be an odor-odor mixture involving "retronasal" and "nasal" olfaction.