Geraniums have been popular garden perennials for a long time, and have lots of devotees. Consequently, there are lots of good sources of information on the internet. A good start is provided by the Open Directory Project's geranium category. For a primer on erodiums, this page from the UK gives a good overview.
Stimulus control is the phenomenon of a stimulus increasing the probability of a behavior (operant response) because of a history of that behavior being differentially reinforced in the presence of the stimulus.
Stimulus-response (S-R) is a classical model of psychology about human behaviour and is popularly known as Classical Conditioning. In other words if an association is created between a stimulus and response, everytime there is a stimulus it automatically triggers the associated response.erms used in Classical Conditioning. Unconditioned Stimulus (US): A stimulus that unconditionally, naturally, and automatically triggers a unlearnt response. Unconditioned Response (UR): A natural, usually unvarying response evoked by a stimulus in the absence of learning or conditioning.