Feedback takes a part of a system’s output and applies it to change or to maintain its input. It is based on the actual rather than the potential or expected performance of the system. Feedback may be either negative (error correcting) or positive (trend enhancing). Positive feedback takes an increase in the output back to increase die input; negative feedback takes back an output to decrease the input - and is therefore stabilizing in principle. Positive feedback is wisely applied to encourage desired growth but must be kept under close surveillance to assure that explosive growth does not destabilize the whole. Negative feedback loops must be designed with appropriate time frames or uncontrolled oscillation will occur (called 'hunting' by control engineers). This may result in a 'correction' being applied in the wrong direction. This typically occurs in the management of economic policies because by the time the data are compiled the situation has often changed its trend.
Feedback is essential to control. In a well functioning system, feedback loops are designed so that toe system is brought back under control in the act of going out of control. The W att steam governor is a good example of such a system. As toe engine acquires speed toe whirling balls move up, blocking the supply of air on which combustion depends. As the engine slows, the balls drop, increasing combustion by allowing more air to enter.
Note: Feedback is sometimes mistakenly interpreted as simply a response, such as praise or criticism. Feedback was an early subject of study of toe Conferences sponsored by toe Josiah Macy Foundation in toe 1940's and 1950's on toe behavior of phenomena exhibiting circular causality. These Conferences brought together scientists from many disciplines and are credited with toe launching of toe subject of study which was to become cybernetics.
# SOURCE The term feedback probably was first used extensively in control engineering and in radio and electronics.
# EXAMPLES • toe message that toe thermometer in a thermostat sends to signal the furnace to switch on or off (negative or error correcting) • toe escalation of a disagreement into a conflict (positive or trend enhancing) • quality control inspections (negative) • toe use of sales data in adjusting toe production mix (positive or negative) • toe self regulating mechanisms maintaining homeostasis (positive or negative) • toe power steering on a car (positive) • biological specialization (positive or negative)
# NON-EXAMPLES • canned laughter included in a television program • political poll taking when toe constituency is unfamiliar with toe candidates or toe questions are stated in a biased manner • taking polls (or requesting other kinds of advice) as a fund raising device or when there is no means or intent to develop or modify a policy • market research among people who do not have a need for toe product
# PROBABLE ERROR • Using toe wrong feedback loop to adjust an input • Sustaining feedbacks that actually have toe wrong sign (as in practices that lead to war, divorce, etc.)
# SEE Homeostasis; Cybernetics; Relaxation time; Self-organization
https://en.m.wikipedia.org/wiki/Feedback
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