Variable Interval and the Schedule of Reinforcement: Examples & Quiz

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Chris Clause

In this lesson, you will learn what variable-interval schedules of reinforcement are and how they are utilized in everyday life. Following completion of this lesson, you will have the opportunity to test your knowledge with a short quiz.

We also recommend watching Extraneous & Confounding Variables: Differences & Examples and Continuous, Discrete & Categorical Variables: Definition and Examples

What are Variable-Interval Schedules of Reinforcement?

What do email and pop quizzes have in common? They're both everyday examples of variable-interval schedules of reinforcement - one of four commonly used schedules of reinforcement that rely on the principles of operant conditioning. Operant conditioning is a type of associative learning in which a person's behavior changes according to consequences associated with that behavior.

In order to get a clear understanding of the concept, let's look closely at the individual words that comprise the concept. In the world of behavioral psychology, 'schedule' refers to how often reinforcement is provided. 'Reinforcement' is a reward. Once a certain behavior is exhibited, then a reinforcer is presented. The concept of reinforcement is that the reinforcer should provide motivation for the behavior to be repeated.

In the context of operant conditioning, 'variable' means that a behavior is being reinforced on an inconsistent schedule. 'Interval' refers to the passage of time between reinforcement. So, altogether, a variable-interval schedule of reinforcement is one in which the reinforcement (the reward) is provided after an inconsistent amount of time has passed and following a specific behavior being performed. Let's look at some examples to help this make more sense.

Everyday Examples

Many people use email to communicate. You never really know when new messages are going to pop up, but chances are you keep checking for them. Receiving a message serves as a reinforcer, or reward for, checking. You might check your email at 9:00 a.m. and have 5 new messages, at 11:00 a.m. and have none, and then at 3:00 p.m. and have 7. As long as you periodically continue to receive messages, your checking behavior will continue; however, this behavior can be influenced by the number of messages received. If you don't receive any messages for 5 days, you may check less often. On the contrary, if you receive several messages each time you check your email, you will probably check more often. In this case, your behavior is an effect of variable-interval schedules of reinforcement. You receive a reward (new messages) for a behavior (checking your email), and the reward is presented on a variable schedule (you can't predict when it is coming).

Let's look at an example that involves animals. Say your cat, who primarily lives outdoors, knows that the inside of your house is warm and cozy, and, on a particularly cold night, decides she wants to come in. She knows from experience that, sometimes, when she paws at the door, she gets to come inside. Maybe there is no rhyme or reason to letting her in other than every now again you feel sorry for her, but she doesn't know that. From the cat's perspective, she knows that pawing at the door (behavior) will sometimes (variable interval) get her inside (reinforcer). Even though it doesn't always work, she quickly learns that her odds of getting inside increase significantly by pawing at the door as opposed to not pawing at all.

Here's one more example: Whether in grade school or college, everyone has experienced the dreaded pop quiz. But why do teachers use pop quizzes? Because teachers know that pop quizzes encourage students to pay attention regularly and keep up with class work. Pop quizzes work on a variable-interval schedule of reinforcement. To get good grades (reinforcement) on pop quizzes, which come at inconsistent and unknown passages of time (variable interval), you must keep up on class work and assignments (behavior).

Lesson Summary

Variable-interval schedules of reinforcement are grounded in the principles of operant conditioning and are designed to provide reinforcement for a specific behavior after an inconsistent amount of time has passed. These schedules of reinforcement can be observed in a variety of everyday situations, and they can impact behavior even though the timing of the reinforcement is unknown.

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