Lability of odor pleasantness: influence of mere exposure.

Subjects judged the pleasantness of various odorants both before and after intensive exposure to a pleasant, a neutral, or an unpleasant odorant, or a short period of relaxation. Intensive exposure comprised a 30 min task of intensity discrimination. The outcome implied that exposure to an odorant can modify its own pleasantness readily, but not so readily that of other odorants. Exposure to the pleasant lemon-smelling substance citral reduced its subsequent pleasantness, whereas exposure to the unpleasant rancid-smelling substance isobutyric acid reduced its subsequent unpleasantness. The results were compatible with the notion of affective habituation. Variability of the pleasantness judgments was uniform throughout the hedonic continuum. That is, subjects agreed as much about hedonically neutral odors as about extremely pleasant and unpleasant odors.