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.
Rating Newest Oldest. Best Answer: A stimulus is a change in internal or external environment of the body, detected by sense organs. They can be mechanical(touch, pain, pressure etc), thermal, chemical(odorants, food etc). Certain chemical like odorants can cause change in the receptor cells i.e. chemoreceptors. Examples are: