feedback

Feedback occurs when outputs of a system are “fed back” as inputs as part of a chain of cause-and-effect that forms a circuit or loop. The system can then be said to “feed back” into itself. The notion of ’cause-and-effect’ has to be handled carefully when applied to feedback systems: “Simple causal reasoning about a feedback system is difficult because the first system influences the second and second system influences the first, leading to a circular argument. This makes reasoning based upon cause and effect tricky, and it is necessary to analyze the system as a whole.” In this context, the term “feedback” has also been used as an abbreviation for: Feedback signal the conveyance of information fed back from an output, or measurement, to an input, or effector, that affects the system. Feedback loop the closed path made up of the system itself and the path that transmits the feedback about the system from its origin (for example, a sensor) to its destination (for example, an actuator). Negative feedback the case where the fed-back information acts to control or regulate a system by opposing changes in the output or measurement.