Which of the following is NOT considered a characteristic of operant conditioning?

Operant conditioning is a learning process where behaviors are modified through the use of consequences, which can include rewards or punishments. This form of conditioning focuses on voluntary behaviors—actions that are under the control of the individual.

The core characteristic of operant conditioning is that it involves an association between a behavior and its consequences. Rewards or reinforcements increase the likelihood of the behavior being repeated, while punishments decrease that likelihood.

However, the association between two stimuli, as mentioned in the context of classical conditioning, is not a feature of operant conditioning. In classical conditioning, learning occurs through the association of two stimuli, leading to a learned response. This fundamental distinction is why the mention of associating two stimuli does not fit within the framework of operant conditioning. Therefore, it stands as the correct answer in identifying what is not characteristic of operant conditioning.