1) Presenting a reinforcing stimulus when a response occurs, or arranging such presentation.

2) Operant behavior refers to those performances which are increased in frequency by operant reinforcement. Operant performances are to be contrasted with reflexes, when the environment elicits a change within the organism. In general, an operant refers to a class of behaviors rather than a single performance. Thus, an operant performance might designate a specific instance of a performance while an operant designates a class of performances maintained by a common reinforcer. When we say, for example, "The food magazine reinforced a whole class of performances which had the common property of moving the treadle far enough to operate the electrical switch," we are expressing the concept of a class of operants. Colloquially, we could speak of these treadle performances as feeder-operating behaviors. A similar connotation is carried by the expression, "attention-getting behaviors." The performance is actually defined by the reinforcer it produces.