If a controller has been tuned properly, and deviations of PV from the SP are still excessive, it may be the result of the disturbances being too severe to be handled solely by feedback control.

A subset of individuals who become preoccupied with sexual fantasies and urges act on these impulses while feeling that they have no control over ... pursuit of feedback or reward these activities ...

An example of negative feedback is the control of body temperature. Body temperature is controlled by the hypothalamus in your brain, and if your body gets too hot, your body begins to sweat to ...