Garcia effect: what is it and what does it tell us about classical conditioning?

A summary of the Garcia effect, a psychological phenomenon investigated from behaviorism.

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

But why does this happen? It can be explained by the Garcia effecta 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.

Garcia effect: what does it consist of?

The Garcia effect is a phenomenon found within classical conditioning, which alludes to the fact that an exteroceptive Conditioned Stimulus (CS) (e.g. a light or a sound) is more easily associated with an exteroceptive Unconditioned Stimulus (IS), and that an interoceptive CS (e.g. a type of food) is more easily associated with an interoceptive IS.The effect is that an interoceptive CS (e.g. a type of food) is more easily associated with an interoceptive IE.

An example of this effect would be when we feel stomach pain, or nausea, and then we relate it to something we have eaten; it does not matter if the pain or nausea is caused by any other external reason, most of the time we will relate it to food.

This happens because there is a selective conditioning according to the type of stimulus; that is to say, we associate the nature of the stimulus with food.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 aversive conditioning to taste can be found around the 1940's. In order to carry out these studies, poison was used to eradicate rat and mouse pests. Recall that aversive conditioning involves learning a rejection response to some type of stimulus.

Specifically, this type of conditioning 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 "Garcia 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 with rats, J. Garcia applied ionizing radiation to them to provoke gastric pain. He then observed how the rats stopped drinking water from the plastic bottle, as they had associated the stomach ache (conditioned had associated the stomach ache (internal conditioned response) with the plastic water bottles (internal conditioned stimulus)..

He also studied this with food, and the effect was the same. This occurred even if the cause of the belly ache was something else. According to him, and what defines the Garcia effect itself, the rats associated these two stimuli (which, in reality, had nothing to do with each other, because the tummy ache was caused by another stimulus, ionization), because they had the same internal nature.

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

Variations in the experiments

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

He found that the rats still rejected the water (in this case, with a new flavor), but did not reject the red light contained in the container. This last phenomenon reinforces the fundamental idea of the Garcia effect, which alludes to the nature of the stimuli, considering that they must be the same for conditioning to occur (in this case, the light is an external stimulus, and the gut pain is internal).

Rejection of his research

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

Characteristics of psychological phenomena

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

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

In contrast, they did not associate pain with external stimuli (e.g. a red light), even if they were paired in time; this is because the Garcia effect defends the association of stimuli of the same nature.

In addition, another novelty proposed by J. Garcia another novelty proposed by J. Garcia was that the time interval between the stimuli that occurred between the conditioned stimuli (in this case, the taste and smell of the food) and the unconditioned response (stomach ache) that is finally conditioned (the rejection of the food), was prolonged.

This interval could be as long as 6 hours. In other words, it could take up to 6 hours from the time the animal ate to the time it suffered the belly ache, and the conditioning and learning that "the food has caused me this pain, therefore I reject the food" took place anyway. Finally, the Garcia effect is a phenomenon that is resistant to unlearning, i.e. it is difficult to extinguish (it is difficult to make it disappear).

Examples in everyday life

Another characteristic of the J. Garcia phenomenon is that the fact that the animal (or person) knows that the reaction or discomfort (tummy ache) is caused by an illness (e.g. flu or cancer), does not prevent it from continuing to reject the food.

This is also observed in Cancer patientsIn the case of animals that have been treated with chemotherapy, they develop a rejection towards 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 the nausea and vomiting, its organism 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. Garcia observed how they generated a conditioned rejection response to poisoned food. To achieve this conditioning, as in the case of rats, a single exposure was sufficient, a single exposure was sufficient to achieve this conditioning, as in the case of rats..

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

Bibliographical references:

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