Information Systems : Feedback

In some information systems, the outputs that the system produces can generate further inputs. When the outputs of a system affect its inputs we say that feedback is occuring. Our model can be extended to incorporate feedback like this :

Feedback occurs in two different types of information systems :

System Type	Explanation
Control Systems	Computerised control systems use sensors to gather data. They switch devices on and off based on the data gathered. A control system for a greenhouse could incorporate a temperature sensor which measures the temperature in the greenhouse and a heater to warm it when it is cold. When the system detects it is cold the heater is turned on. This changes the temperature. The output (heat) affects the input (temperature) so feedback occurs.
Turnaround Documents	Some information systems produce as output forms which the user must fill in. When the user has completed a form the extra information added onto it is entered into the computer. These documents are known as turnaround documents. Because the completed output forms are used to produce new inputs feedback occurs.

GCSE ICT Companion 04 - (C) P Meakin 2004