Taste aversion
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Conditioned Taste Aversion is an example of classical conditioning, also called Pavlovian conditioning. Conditioned taste aversion occurs when a subject associates the taste of a certain food with symptoms caused by a toxic, spoiled, or poisonous substance. Generally, taste aversion is caused after ingestion of the food causes nausea, sickness, or vomiting. The ability to develop a taste aversion is considered an adaptive trait that trains the body to get rid of poisonous substances (e.g., poisonous berries) before they can cause harm. This association will hopefully prevent the consumption of the same substance (or something that tastes similar) in the future, thus avoiding further poisoning. However, conditioned taste aversion sometimes occurs in subjects when sickness was merely coincidental and not related to the food (For example, a subject who gets a cold shortly after eating bananas might develop an aversion to the taste of bananas).
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[edit] Garcia’s study
Conditioned taste aversion was studied by Dr. John Garcia.. Garcia ‘’’conditioned’’’ rats to develop taste aversion to sweetened water, a substance that rats generally consume in higher quantities than tap water. In one study, Garcia had three main experimental conditions. In the control condition, rats were given access to sweetened water with no interference. In a second condition, the rats were given access to the sweetened water then exposed to a mild dose of radiation some time after. In the third condition, the rats were give access to the sweetened water and then exposed to a higher dose of radiation. Radiation is an unconditioned stimulus that tends to elicit nausea. Note that rats do not have the ability to vomit.
All three groups of rats were then given a choice of sweetened water or unsweetened water and Garcia measured the amount of each that the rats consumed. The rats in the control condition drank just over 80% sweetened water (20% unsweetened); those in the mild radiation condition drank nearly 40% sweetened water; those in the high radiation condition drank less than 10% sweetened water. Thus, especially for the high radiation rats, when associated with nausea the sweetened water became aversive.
[edit] Interesting notes concerning taste aversion
Taste aversion does not require cognitive awareness. That is, the organism does not have to think, “Wow, this tastes like that stuff that got me sick.” In fact, the organism may ‘’’hope’’’ to enjoy the substance but the body handles it reflexively. Conditioned taste aversion illustrates the argument that in classical conditioning, a response is elicited.
Also, taste aversion generally only requires one trial. The experiments of Pavlov required several pairing of the neutral stimulus (e.g., a tuning fork) with the unconditioned stimulus (i.e., meat powder) before the neutral stimulus elicited a response. With taste aversion, after one association between sickness and a certain food, the food may elicit the response. In addition, lab experiments generally require very brief (less than a second) intervals between a neutral stimulus and an unconditioned stimulus. With taste, however, the bratwurst a person eats at lunch may be associated with the vomiting a person has in the evening.
[edit] Taste aversion in humans
Taste aversion is fairly common in humans. When humans eat bad food (e.g., spoiled meat) and get sick, they may find that food aversive until extinction occurs, if ever. Also, like in nature, the food does not have to ‘’’cause’’’ the sickness for it to become aversive. A human who eats sushi for the first time and happens to come down with a stomach virus or influenza not related to the food may still develop a taste aversion to sushi.
Taste aversion is a common problem with chemotherapy patients who get nauseated because of the drug, but associate the nausea with the food he or she is eating.
[edit] Applications of taste aversion
Taste aversion has been demonstrated in a very wide variety of both captive and free-ranging predators. In these studies, animals that consume a bait laced with an undetectable dose of an aversion agent avoid both baits and live prey with the same taste and scent as the baits. When predators detect the aversion agent in the baits, they quickly form aversions to the baits but discriminate between these and different-tasting live prey. The use of conditioned taste aversion in wildlife management has been resisted by wildlife governmental wildlife managers mainly because of a lack of understanding of the process. For further information on this topic, see www.conditionedtasteaversion.net.
[edit] Stimulus generalization
Stimulus Generalization is another learning phenomenon that can be illustrated by CTA. This phenomenon demonstrates that we tend to develop aversions to even to similar types of food that look like the foods that cause us illnes. For ex: If we eat an orange and get sick, we might avoid eating Tangerines and clementines as well because they look similar to oranges and might lead us to think that they are also dangerous.
