Stimulus control is the phenomenon of a stimulus increasing the probability of a behavior (operant response) because of a history of that behavior being ifferentially reinforced in the presence of the stimulus. In other words, stimulus control is basically learning to pay attention to things that we identify in the environment (discriminative stimuli) that give us information about the effectiveness of our behavior: what behavior is likely to be effective or ineffective, under which conditions, and what does that behavior give us (reinforcement or punishment). Therefore, in the presence of those stimuli we are likely to respond differentially.