a student gets into the habit of responding in a certain way when prompted
Notably, this is a habit and the student doesn't have to think or work out what to say, it just comes naturally.
So, in the same way that the student knows that when the bell rings, the lesson is over, when the teacher says How are you? the automatic response is Fine, thank you, and you?
In the context of learning, the behaviorist model for learning is all about "do as I say" and very much teacher-centered.
Behaviorists saw language as something that could be broken down into a mass of habits and once each was learned, then the language was learned. This approach, though effective for some, neglected somehow the usage of language in the real world, since the language taught is not presented as a natural activity, but rather as a set of isolated sentences which are practiced to memorize a form. Additionally, this method does not cater for gifted students who need more learning challenges.
There are two main strands to behaviorism in teaching.
Simply put this is when a neutral stimulus calls for an automatic response.
In TEFL this means teaching simple phrases which are practiced over and over again until they become automatic and don't require any thought. Entire conversations can be developed like this.
This is slightly more involved and is about using punishment or rewards for certain behaviors.
The student doesn't do their homework and they are punished. After time they will learn that not doing homework will lead to punishment so they do their homework. (That's the theory, anyway!)
On the other hand, they also learn that doing something well will lead to a reward.
Pavlov and his dogs was one of the first psychologists looking into this field. During the 1890s he carried out a number of experiments on dogs whereby he taught them to associate the sound of a bell ringing with food. Each time the bell rang, the dogs began to salivate. This was a learned reaction.
Later the American psychologist B. F. Skinner, regarded as one of the most influential psychologists of the 20th century and the father of Behaviorism, argued that cause and effect is what controls behavior, not the mind or reasoning.
TEFL Methodologies - an overview of different methologies