Learned Taste Aversion

Introduction:
A learned taste aversion is the aversion developed by an individual for a certain food that caused him an illness. John Garcia first discovered this phenomenon during his experiments on rats. After classical conditioning, rats associate the taste of the food (CS) with getting sick (UC). They therefore create an aversion for that specific taste. Garb and Stunkard (1974) conducted a study on learned taste aversion. They sent a questionnaire about such experience to 700 people. The results allowed Garb and Stunkard to confirm the basic properties of learned taste aversion in humans:
1. “Belongingness”: aversion is always limited to the food and its taste. The aversion results most of the time from a gastrointestinal illness.
2. “One-trial learning”: One pairing of food and illness is sufficient to create aversion that last for many years.
3. “Long CS-US interval”: interval of several hours between ingestion of the food and the first symptoms.
4. “Novelty”: Foods have not been eaten more than once or twice before the association with illness (45% of the time).
5. “Irrationality”: The fact that the knowledge that the food was not responsible for the illness does not weaken the aversion.

This paper will discuss the methods, findings and interpretation of the interview of three persons who have experienced a ‘learned taste aversion’.
Methods:
I started by asking the first UCU students I came across whether they had ever experienced a learned taste aversion. I explained to them the basic phenomenon of taste aversion (without mentioning Garb’s and Stunkard’s five basic properties of learned taste aversion). I also made them read the introductory statement to make sure they understood the concept correctly. Three out of the five people I asked confirmed they already have a taste aversion. They were thus selected as my participants. Each participant sat at the table and received a questionnaire to fill in. I would only interact with the volunteer when he would have a question concerning the questionnaire. Findings:
Participant 1, a 21-year-old male, was 19 when he experienced a “learned taste aversion”. His stepmother cooked him homemade pesto, as she already did several times in the past. He ate the pesto with bread for dinner that night. He became sick about 10 minutes after eating the meal. He was vomiting and had nausea during the whole night. Participant 1 blames the homemade pesto for his illness and has had an aversion to the smell since then. However, he does not mind tasting, smelling or seeing commercial pesto. His aversion sticks to homemade pesto only.
Participant 2 is a 19 year-old female. She experienced a learned taste (and smell) aversion to cheese flavored “Doritos” when she was 10. She has had this aversion ever since she got sick after her cousin’s birthday. She ate a large quantity of “Doritos” at the party and started vomiting when she arrived home, approximately three hours later. Although she also ate chocolate cake and candies at the birthday, she is convinced that they were not responsible for the illness and therefore did not develop an aversion for these foods.
Participant 3, a 20-year-old, acquired an aversion to fried noodles with sour sauce when he was 19. He ate a large portion of fried noodle with sour sauce, which he ordered, from a cheap Asian restaurant in Vienna. He started vomiting about three hours after eating the food. He blames the quality of the food for his illness. He has an aversion to the smell as well as the taste of fried noodles with sour sauce. Participant 3 claims he will never eat this meal again unless it is cooked in a restaurant he can totally trust.
Observation and interpretation
Through observing and interpreting these findings, we can see if the participants’ experience confirms Garb and Stunkard’s basic properties of learned taste aversion (see introduction).

All the subjects blame one food from their meal for their illness. No other factor than the quality and/or the quantity of the food can be held responsible for the illness, which they experienced. The food was paired with illness after only one negative experience for each of the subjects. These findings support the “one-trial learning” basic property.
The participants could be considered irrational. They know that the illness was probably only due to the excessive quantity (for subject 2 and 3) and/or to the quality of the food (for subject 1 and 3). Yet they acquired a strong aversion to that food in general. It is interesting to observe the various levels of aversion to the different foods. On one hand, Participant 2 avoids any contact with cheese flavored Doritos. Participant 1 on the other hand strictly limits his aversion to homemade pesto. He does not mind eating industrial pesto. Finally, participant 3 confirms he would be ready to eat fried noodles with sour sauce again, as long as “it comes from a reliable restaurant”.
The illness always involved the gastrointestinal system seeing each of subject’s illness involved vomiting (and also nausea for participant 1). These findings support the property of belongingness. However, the participants do not restrict the taste as the CS associated with the illness (US), as observed by Garcia: only participants 2 and 3 acquired an aversion for the food’s taste. Participant 1 does not mind the taste, but does mind the smell of homemade pesto and therefore appears to allow an exception to the phenomena. Interestingly, all the participants have a strong aversion for the food’s smell.
The data from the questionnaire filled by subjects 2 and 3 also supports the “long CS-UC intervals” property. However, participant 1 appears once again as an exception seeing the interval was only measured in a few minutes before he had the first symptoms of illness.
The property of novelty is not exactly respected. Only subject 2 (33% of the participants) had eaten the food less than 2 times before. It is nevertheless important to point out that such a small sample size can obviously not be representative of a larger population. We could therefore not expect to have the same statistics for a sample of 3 participants as for a group of 700.
We can conclude that the properties of learned taste aversion described by Gab and Stunkard have been confirmed in the cases of subjects 2 and 3. On the other hand, subject 1 appears as an exception since his experience does not include the long interval between UC and US, and the aversion to the taste.

Reference
Garb, F., and Stunkard, A. (1974). Taste aversions in Man. American Journal of psychiatry 131, 1204-1207.