The term we are going to talk about today is a pretty important one; Stimulus Control. It’s a term used in behavioral psychology (behaviorism) to describe the relationship between an antecedent stimulus (setting, etc), and the control (or altering effect) it has over the behavior that follows it. Another way to phrase it is, stimulus control is a phenomenon that occurs when an organism behaves one way in the presence of a stimulus, and differently when it is not present. 
The stimulus itself in this situation is called the discriminative stimulus (sometimes written as SD ). A discriminative stimulus is a stimulus in which a prior behavior had undergone either reinforcement (strengthening its future use) or punishment (weakening its future use) in the past, leading to how that behavior is adaptively used in a condition (stimulus) that is similar to it in the future. We are describing what factors have a controlling effect on behavior, due to their history. [1,2]
So, in the presence of this discriminative stimulus, a behavior might exhibit changes in frequency, duration, amplitude or intensity, and how quickly or slowly it occurs following that discriminative stimulus. [1,2]
Let’s look at some examples:
Let’s say the discriminative stimulus is an itch. The person has a history of relieving that itch successfully by scratching it. So, what behavior (response) comes under stimulus control of the itch? Scratching. In the presence of the itch, the scratching behavior is likely to occur. That, is stimulus control.
How about this one? It’s now 7 PM on a Thursday. In the past, at 7 PM on Thursdays, a favorite show comes on television. What behavior (response) might come under stimulus control of that discriminative stimulus (the favorite show being on)? There might be a few, or a chain, you could say; sitting down, turning on the TV, flipping to the channel. All of these behaviors are under the stimulus control of it being 7 PM on a Thursday, and having been reinforced (rewarded) in the past.
How many conditions can you think of that would show this relation? Plenty, right?
Countless behaviors fall under stimulus control. That’s what makes it such a fascinating topic and definition.
Questions, Comments? Leave them below!
1.Baum, William M. (2005). Understanding behaviorism : Behavior, culture, and evolution
2. Cooper, J. O., Heron, T. E., & Heward, W. L. (1987). Applied behavior analysis. Columbus: Merrill Pub. Co.
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