The controlling effects of stimuli are seen in quite diverse situations and in many aspects of behavior. For example, a stimulus presented at one time may control responses emitted immediately or at a later time; two stimuli may control the same behavior; a single stimulus may trigger behavior A at one time and behavior B at another; a stimulus may control behavior only in the presence of another stimulus, and so on. These sorts of control are brought about by a variety of methods and they can explain many aspects of behavioral processes.[4]
In simple, practical situations, for example if one were training a dog using operant conditioning, optimal stimulus control might be described as follows:
Matching to sample[edit]
In a typical matching-to-sample task, a stimulus is presented in one location (the "sample"), and the subject chooses a stimulus in another location that matches the sample in some way (e.g., shape or color).[11] In the related "oddity" matching procedure, the subject responds to a comparison stimulus that does not match the sample. These are called "conditional" discrimination tasks because which stimulus is responded to depends or is "conditional" on the sample stimulus.
The matching-to-sample procedure has been used to study a very wide range of problems. Of particular note is the "delayed matching to sample" variation, which has often been used to study short-term memory in animals. In this variation, the subject is exposed to the sample stimulus, and then the sample is removed and a time interval, the "delay", elapses before the choice stimuli appear. To make a correct choice the subject has to retain information about the sample across the delay. The length of the delay, the nature of the stimuli, events during the delay, and many other factors have been found to influence performance on this task.[12]
Cannabinoids[edit]
Psychoactive cannabinoids produce discriminative stimulus effects by stimulation of CB1 receptors in the brain.[13]