ABA applies an understanding of how behavior works to real life situations. But how do we determine what that behavior is, and more importantly, what is causing the behavior? In simple terms, we go back to the ABCs…the antecedent, behavior and consequence. The ABCs are also known as three and four term contingency. This is a very familiar spot for most of us. The ABCs are, after all, the building blocks of ABA. If the phone rings (the antecedent) then we will typically answer the phone (the behavior) and if it is a friend then we have a positive consequence. However, if it is a telemarketer then we have a negative consequence. The next time the phone rings we may react differently based on the positive or negative consequence.
Three Term Contingency
The three term contingency is another way of describing the ABCs. We start with the SD, or the discriminative stimulus. This is typically some type of lesson that we are teaching, or in our example it is the phone ringing. It is what conditions our behavior. The SD is equivalent to the antecedent, it is what comes before. Then we have a response, or the behavior. Sometimes this is a positive response if our client likes the antecedent or it could be a negative response which we want to change. And lastly we have the SR or the SP. The SR, or reinforcement results in a positive experience while the SP, or punishment results in a negative experience.
Four Term Contingency
The four term contingency follows the same basic structure as the three term contingency, but digs a little deeper into the environment of the client by determining the establishing operation or EO. The EO takes into account the motivation for the client. This motivation plays a huge role in increasing or decreasing the behavior. It also considers events or things that may have happened before the antecedent was ever presented. For example, if the student is having a bad morning and then you present them with a demand, then they are already motivated by escape and more likely to not be compliant. But, when they are having a good morning, they may be more likely to try the reading lesson, etc.
The EO can be captured or contrived. When captured it is happening in the moment. The client may ask for something and you can use that want as motivation to get a desired behavior first. Whereas a contrived motivation is created. You will tell them they will get something by completing a task. For example, getting a client to willingly put their coat on because they can go to the park on a cooler day. Creating motivation, whether contrived or captured, before you begin teaching will increase the likelihood of getting what you want out of the student.
Which is Better?
Identifying both three and four term contingencies can make a difference in the progress of your client. And while they are very similar, we feel that it is always best to dig a little deeper and find motivation for the client and identify that EO. This results in an increase of positive results…which is always our end game.