By Delta stimuli reduce punished behaviors and are essential in a variety of contexts, from eating a treat to understanding signals. We invite you to learn more about this theory.
In the behaviourist framework, a stimulus is a signal that influences an organism’s responses and its senses. There are different types in the environment, including: discriminative, evocative, reinforcing, conditioned-unconditioned and delta stimulus (S-delta).
S-deltas get their name from being present at the moment when a response is not reinforced. To understand this better, imagine that you go to a vending machine to buy a candy and you notice that the products are marked with red and green lights. If the green light is on, it means that the product is available; if the red light is on, it means that the candy is sold out.
In this example, the green light (discriminative stimulus) would trigger a behavior: press the button to get the candy. On the other hand, the red light (delta stimulus) would not trigger a response. Therefore, if it were red, you would inhibit yourself from putting money into the machine. Let’s delve deeper into this topic.
What is a delta stimulus?
According to Mallott and Kohler (2021), a delta stimulus is characterized by the fact that responses are not reinforced or punished in its presence. For example, the absence of friends for a child can be a S-delta, since without them he will not get reinforcement for certain behaviors. So would the presence of his parents, with whom he will intuit that they will not reinforce some responses that his friends would make.
When we talk about there being no consequences, we are referring to the lack of any procedure or strategy capable of increasing ( reinforcements ) or decreasing ( punishments ) the frequency of occurrence of a behavior.
For operant conditioning , the perpetuation or extinction of a behavior depends on its consequences. In the case of S-delta, there is no association between the response and its consequences, since they are not present. The stimulus appears, but not the effect on the organism.
Thus, delta stimuli increase the probability of inhibiting a response, since the organism does not anticipate a reinforcement if it performs the response or a punishment if it does not perform it. If it were used to anticipate that a certain action will have negative effects (a punishment) or positive effects (a reinforcement), then it would no longer be a S-delta, but a discriminative one.
Characteristics
Some of the most relevant characteristics of delta stimuli are listed below:
- They are not associated with any type of consequence.
- In its manifestation, the behavior does not receive reinforcements.
- They increase the likelihood that a response will not occur.
- They reduce the frequency of punished behaviors in their presence.
- They function as a signal that a specific response will not be issued.
How are delta stimuli evident?
Since S-delta is often confused with other types of stimuli, we have compiled four examples that will help clear up any doubts about it.
1. Understanding signs
A person sees an “Out of Order” sign when trying to enter a restroom. The sign operates in this case as a delta stimulus.
2. Bad behavior
A child exhibits disruptive behavior in the presence of his mother, but does not exhibit any of these behaviors when he is with his grandmother. In this case, the grandmother is an S-delta, since no response is produced in front of her.
3. Learning
A child looks through a book about means of transport with his mother, learning to recognize those that travel on land. Every time he identifies them correctly, his mother hugs and kisses him; however, when he points out a non-land transport, his mother does not hug him, but she does not punish him either. In this case, the non-land transports operate as S-delta.
4. Training
A pigeon trainer makes two cards: one red and one blue. If the pigeons peck the red card, their behavior is reinforced; if they peck the blue card, that behavior is not. At first the pigeons will peck both cards, but eventually they will only peck the one that triggers a reward (the red one). The blue card operates in this example as S-delta.
Link between delta and discriminative stimulus
A discriminative stimulus increases the likelihood that reinforced responses will occur in its presence. Thus, a discriminative stimulus tells the organism which behavior to reinforce or punish. That is, it signals the availability of a consequence for a particular behavior.
The rule followed for the control of operant behavior by discriminative stimuli is the following: an operant behavior will occur, with a high frequency, in the presence of a discriminative stimulus that in the past accompanied its appearance and established the occasion for its reinforcement.
Likewise, you can make a response happen less often in those cases where you accompanied its reduction and set up the occasion for its punishment.
The relationship between a delta and discriminative stimulus is best seen with an example. Imagine that when a discriminative stimulus (green light) is present, a response (eating) is reinforced. But when it is not present, the response is neither carried out nor reinforced. Stimuli that are present when the behavior is not reinforced are deltas.
Consequently, S-deltas operate in the opposite direction to discriminative signals, since the latter serve to warn that a behavior will be reinforced or punished, while deltas indicate that it will be neither reinforced nor punished as expected.
Don’t downplay delta stimuli
As we have seen, delta stimuli are signals that do not favor the reinforcement or punishment of a response. Ultimately, they function as a warning that nothing will happen next.
However, even though they operate in this way, they are no less important in our lives, as they are necessary for the actions we perform in certain contexts. Thanks to them, we can know what to expect and what not to expect from our environment.