Measurement of food perception, food preference, and nutrient selection

Perception, preference, and selection are all objectively measurable performances that discriminate between different levels of entities such as the sugar, thickener, or protein in a food. A rating or an intake may not be controlled by the word that the experimenter or the subject uses to describe it: "protein"-oriented food selection, "thickness" preference, or "sweetness" perception is proved only when the named objective influence, isolated from any other influence, accounts for the observed variations in choice response. Difference-measuring designs can be extended from merely two levels of an influence to a continuum over the natural range of levels, thus evoking linear psychophysical (dose-response) performance from which the strength of that influence can be estimated. Usually, at least a few influences are operative at once on a choice. Because the interactions may vary among people, the only valid causal analysis is at the individual level. Examples are given of food taste tolerance in the elderly, integration of sensory and attitudinal influences, and dietary choices misattributed to carbohydrate craving.