Garcia Effect: what it is and what it tells us about classical conditioning

Surely it has ever happened to you that after eating some kind of food and feeling pain in your guts, you end up refusing (consciously or unconsciously) to eat that food again, at least for a while. time.

But why does this happen? It can be explained through the Garcia effect, a phenomenon of classical conditioning.

This phenomenon, discovered by the American psychologist John Garcia in the 1950s, consists of a type of aversive conditioning to taste, which began to be studied with rats. In this article we will learn how this effect was discovered, what it consists of and why it occurs.

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Garcia effect: what is it?

The Garcia effect is a phenomenon that we find within classical conditioning, and that alludes to the fact that an exteroceptive Conditioned Stimulus (CS) (for example a light or a sound) is more easily associated with an exteroceptive Unconditioned Stimulus (US), and that an interoceptive CS (for example, a type of food) is more easily associated with an interoceptive US.

An example of this effect would be when we feel stomach ache, or nausea, and then we relate it to something we have eaten; It doesn't matter if the pain or nausea occurs for any other external reason, most of the time we will associate it with food.

This occurs because selective conditioning occurs according to the type of stimulus.; that is, we associate the nature of the stimulus with the nature of the response, which must be the same (in this case, an internal origin). But how did the discovery of the Garcia effect come about? Let's go to the origin.

Origin of aversive conditioning

The origin of the study of taste aversive conditioning can be found around the 40s. To carry out these studies, poison was used to eradicate pests of rats and mice. Remember that aversive conditioning involves learning a rejection response to some type of stimulus.

Specifically, this type of conditioning we are talking about is associated with the taste or smell of certain foods (which would be the aversive stimulus).

Ten years later, around the 1950s, John Garcia, an American psychologist, became interested in studying aversive conditioning.. He was the creator of the so-called “García Effect”. This psychologist and researcher studied at the University of California (Berkeley) and later began working in San Francisco for the Navy.

John Garcia's Experiments

It was in San Francisco where, through his experiments on rats, J. García applied the same ionizing radiation to them to cause gastric pain. Immediately afterwards, he observed how they stopped drinking water from the plastic bottle, since they they had associated stomach ache (internal conditioned response) with plastic water bottles (internal conditioned stimulus).

He also studied it with food, and the effect was the same. This occurred even if the cause of the belly pain was someone else. According to him, and what defines the García effect itself, the rats associated these two stimuli (which actually had nothing to see, because the belly pain was caused by another stimulus, ionization), because they had the same nature internal.

Thus, the Garcia effect refers to a type of conditioned reflex rejecting certain foods and flavors. In this exposed case, the rejection stimulus would be the water contained in the plastic bottles.

Variations in experiments

John Garcia used another technique to demonstrate the Garcia effect; what he did was change the taste of the water in plastic bottles by adding saccharin to the container. It was thus a new taste for rats. J. García incorporated a red light into the container with the water+saccharin.

He checked how the rats continued to reject the water (in this case, with a new flavor), but they did not reject the red light contained in the container. This last phenomenon reinforces the fundamental idea of ​​the García effect, which alludes to the nature of the stimuli, considering that must be the same for conditioning to occur (in this case, the light is an external stimulus, and the stomach ache is internal).

Rejection of your research

At first, John Garcia's research was rejected by the scientific community because they did not follow the basic principles of classical conditioning, considered these as true. This is why prestigious scientific journals, such as Science, refused to publish their findings.

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Characteristics of the psychological phenomenon

It is interesting to explain the novel contributions that John Garcia made to the field of classical conditioning, based on the phenomenon of the Garcia effect. These also allude to the characteristics of said effect, and were the following:

On the one hand, he determined that conditioning could be achieved only through exposure, and that many exposures did not always need to occur to achieve conditioning or learning. He also held that conditioning was selective; in the case of rats, they associated belly pain (internal response) with food or drink (internal stimulus).

Instead, they did not associate pain with external stimuli (for example, a red light), even though they were paired in time; This is so because the Garcia effect defends the association of stimuli of the same nature.

Besides, Another novelty proposed by J. Garcia was that the time interval that occurred between the conditioned stimuli (in this case, the taste and smell of food) and the unconditioned response (stomach ache) that ends up being conditioned (rejection of food), was dragged on.

This interval could even reach 6 hours. In other words, up to 6 hours could pass from the time the animal ate until it suffered from belly pain, and that anyway forms the conditioning and the learning that “the food has caused me this pain, therefore I reject the meal". Finally, the Garcia effect is a phenomenon that is resistant to unlearning, that is, it is difficult to extinguish (it is difficult for it to disappear).

Examples in everyday life

Another characteristic in the phenomenon of J. García is that the fact that the animal (or the person) knows that the reaction or discomfort (pain of belly) is caused by an illness (for example flu or cancer), it does not prevent you from continuing to reject said meal.

This is also seen in cancer patients., who end up rejecting the food they have consumed prior to a chemotherapy session if the latter has caused nausea or vomiting; Thus, although the person "knows" that the food has not caused nausea and vomiting, his body continues to reject it because it associates it with these symptoms.

Other animals

The Garcia effect was also demonstrated in other animals such as coyotes. J. García observed how these generated a conditioned response of rejection of poisoned food. To achieve this conditioning, as in the case of rats, a single exposure was enough.

They even managed to get coyotes to reject sheep meat by injecting poison into it. In this way, these animals ended up associating gastric discomfort with the taste of meat and therefore finally refused to eat this type of meat. The Garcia effect was also demonstrated in the crows, which, using the same mechanism, managed to get them to refuse to eat the birds' eggs.

Bibliographic references:

• Bayes, R. and Pinillos, J.L. (1989). Learning and conditioning. Alhambra: Madrid.
• Garcia, J., and R. TO. Koelling. (1966). Relation of cue to consequence in avoidance learning. Psychonomic Science, 4: 123-124.
• Garcia, J., Ervin, F. R. and Koelling, R. TO. (1966). Learning with prolonged delay of reinforcement. Psychonomic Science, 5 :121-122.