Discriminatory stimulus: what it is and how it explains human behavior

There are many concepts from behaviorism and behavior analysis.

We have heard of operant response, punishments and rewards, positive and negative reinforcers... but there are certain concepts that are less known despite the fact that they allude to phenomena that occur daily.

The behavioral concept that we are going to talk about today is the discriminative stimulus, that we can anticipate that it is the one that it exerts as "energy" that acts as a warning sign that if something is done there will be consequences. Let's see in a little more detail what it is about.

• Related article: "Behaviorism: history, concepts and main authors"

What is a discriminative stimulus?

In behavior analysis, a discriminative stimulus is any form of stimulation that acquires the property of pointing to a subject, be it a person or an animal, that a Determined behavior that can be carried out will imply a consequence, which may be positive (reward) or negative (punishment).

So we say that something is a discriminative stimulus because it implies a form of "energy" that affects the subject (being a stimulus) and its presence manages to differentiate a response, making it more or less probable depending on the case.

As we have just mentioned, the role of the discriminative stimulus is to indicate that if a certain behavior occurs, a certain consequence will be received. This should not be understood as that the discriminative stimulus is the one that generates the response, but that it simply "warns" that if a behavior is carried out there will be a consequence, both reinforcing as punitive. In other words, the discriminative stimulus is the signal that informs us of the availability of a consequent.

Functional analysis with discriminative stimulus

Let's better understand this idea with the case of Pedro, a store worker. Pedro is in charge of the box, but he has also been assigned other tasks that he does not like, such as ordering the clothes, folding them and watching for any garments in poor condition. One day Pedro goes to his boss and complains about the tasks he has to do. The boss, instead of helping him, scolds him for his complaints and tells him that his job consists of that and that if he doesn't like it, he can leave. Since then Pedro, when his boss is close to him, does not dare to complain for fear that he will be fired.

If we do a quick functional analysis here we can identify three points:

• Operant response: don't complain
• Discriminatory stimulus: presence of the boss.
• Consequent: not receiving a reprimand.

If Pedro complains again when he is in front of the boss, it is most likely that he will scold him for his comments and could even fire him. As a result of all this, Pedro stops complaining when his boss is close to him, which effectively implies that he has reduced the possibility of Pedro carrying out the behavior in question, complaining, with his boss being in front of him, who acts as a stimulus discriminative.

As we have commented the discriminative stimulus does not imply a consequence, but is the signal that this consequence will happen if the behavior is carried out. That is, the presence of the boss does not mean that Pedro is going to be scolded or fired yes or yes, but rather that it serves as a sign of warning that he does not behave in a way that his boss does not like and leads to a reprimand or loss of the job of job.

On the other hand, if Pedro is out of work with his colleagues in a bar and he knows that they don't like his boss either, we have a different situation. Here Pedro will feel freer and will have no qualms about complaining about both his work and his boss. He complains and complains again and his companions support him, reinforcing his behavior even more and making Pedro continue to complain until he can vent. Here the discriminative stimulus is the companions.

• Operant response: complain
• Discriminatory stimulus: presence of peers.
• Consequent: receive support.

In other words, if Pedro complains about his boss in front of his colleagues while outside of work, he will have as a consequence receive his support and, therefore, this behavior will be reinforced.

Other examples

There are countless examples that help us to better understand the idea of ​​the discriminative stimulus.

For example, Let's imagine that we go outside and see that the sky is cloudy (ED1) and we feel a little cold (ED2). Because of this we decided to go back into the house, we take an umbrella (RO1) and put on our jacket (RO2), so in case it rains we will not get wet (C1) and we will not be cold (C2). That is to say, that the sky is cloudy and it is cold increases the chances that we will take an umbrella and wrap ourselves up and, as a consequence, we avoid being cold and getting wet.

Another case is the typical scene of a mother taking her son to a psychologist because at school they have complained that she behaves very badly. She tells the professional that at home she behaves well, that she does absolutely nothing wrong, but that at school they say that she messes up a lot. What actually happens is that the child, if he misbehaves at home in the presence of his mother (ED) she will punish him very severely (C), and for this reason he chooses to behave well at home (RO).

• You may be interested in: "Pavlov's Stimulus Substitution Theory"

Relationship with the delta stimulus

In functional analysis there is another concept that is related to the discriminative stimulus, but in a sense that could be said as the opposite: the delta stimulus. This type of stimulus informs us of the unavailability of a consequent to a certain behavior, neither positive nor negative.

Relating it to Pedro's case, if he is alone in the bathroom and he knows that no one is going to listen to him, he will complain aloud about his boss. In this case, no one scolds him for his complaints, but he does not support him either, he receives absolutely nothing as a result of his criticism.

So we can see the difference between the discriminative stimulus and the delta. In the case of the discriminative, there is a consequence that influences the conduct of the subject, increasing or reducing it depending on whether he receives a reward or punishment for committing it. Instead, in the delta stimulus there is no consequent, directly serving as a sign that whether or not the behavior is performed there will not be in any way a reward or punishment for it.

The union of both types of stimuli can be seen in a classic experiment with rats. Imagine that we have one of these little animals in a cage where there are two lights: one green and one red. When the green light comes on (ED), in case the rat presses a lever (RO), a chunk of feed (C) will be dispensed. Thus, when the animal associates pressing the lever with the green light on with receiving food, it is quite likely that it will press the lever each time that light comes on.

But what happens when the red light comes on? In this case the animal does not receive food, whether you press the lever or not. Namely, the red light on acts as a delta stimulus, a sign that nothing will happen after the stimulus is presented, no matter how much the animal presses the lever again and again. Thus, as the red light turns on so many times, the animal will associate that it is useless to press the lever in that case, this behavior extinguishing with the passage of time because there is neither positive reinforcement nor negative.

Bibliographic references:

• Domjan, M. (2010). Basic principles of learning and behavior. Madrid: Thomson.
• Labrador, F. J. (2008). Behavior modification techniques. Madrid: Pyramid.