Flavor-avoidance learning

Food preferences also can be learned, and, like learned aversions, conditioned preferences can be used to evaluate chemosensory abilities. Typically, preferences are induced by pairing the ingestion of a novel flavor with calories (Bolles et al. 1981 Messier White 1984 Booth 1985 Mehiel Bolles 1984, 1988 Simbayi et al. 1985), recovery from nutritional deficiency (Garcia et al. 1967 Zahorik et al. 1974), and recovery from malaise (Green Garcia 1971 Zahorik 1977 Sherman et al. 1983). The novel flavor is subsequently preferred, as are other flavors that subjects perceive as similar to the conditioned stimulus. However, 

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Flavor consists of taste and odor combined. Animals often avoid tastes after only one experience if delayed illness follows it, but odors are not avoided under such circumstances. If an odor and a taste are presented together before an illness is induced experimentally (e.g. with lithium chloride), animals can learn to avoid the odor after just one such experience. When the odor is intensified in such a combined presentation, only the odor aversion increases, not the taste aversion. If the taste is made more intense, both odor and taste aversions increase. As a rule, the odor aversion strength depends on the taste experience, but not vice versa (Garcia etal, 1986). 

The name given to a set of transient symptoms noted after dining on Chinese food or other highly flavored foods. The symptoms include headache, neck and chest pain, palpitations, and numbness. Monosodium glutamate (MSG), a food additive in high favor in most such restaurants, is the cause. An estimateci 30% of consumers are affected. Sufferers soon learn to avoid excess consumption of highly flavored Chinese foods (especially the soup course). 

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