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- For other uses, including see Feedback (disambiguation)
Feedback is (generally) information about actions.
In cybernetics and control theory, feedback is a process whereby some proportion or in general, function, of the output signal of a system is passed (fed back) to the input. Often this is done intentionally, in order to control the dynamic behaviour of the system. Feedback is observed or used in various areas relevant to psychology.
Lines are usually drawn, directed from input through the system and to output. The feedback is shown by another arrowed line, directed from output outside the system to an input, resulting in a loop on the diagram, called feedback loop. This notion is important; for example, the feedback loop is a convenient place for a control device.
The following is an example of a feedback loop used in web-based workflows. Feedback Loops are established by ISPs for permission e-mail marketers to manage subscribers who click the "This is Spam" button in their web mail clients. The Feedback Loop sends a message back to the marketer letting them know to unsubscribe the subscriber.
Types of feedback
Types of feedback studied by psychologists include:-
- Auditory feedback
- Augmented feedback
- Delayed auditory feedback
- Delayed feedback
- Intrinsic feedback
- Knowledge of performance
- Knowledge of results
- Negative feedback,
- Positive feedback
- Sensory feedback
- Visual feedback
Feedback may be negative, which tends to reduce output (but in amplifiers, stabilises and linearises operation), or positive, which tends to increase output. Systems which include feedback are prone to hunting, which is oscillation of output resulting from improperly tuned inputs of first positive then negative feedback. Audio feedback typifies this form of oscillation.
In economics and finance
A system prone to hunting (oscillating) is the stock market, which has both positive and negative feedback mechanisms. This is due to cognitive and emotional factors belonging to the field of behavioral finance. For example,
- When stocks are rising (a bull market), the belief that further rises are probable gives investors an incentive to buy (positive feedback); but the increased price of the shares, and the knowledge that there must be a peak after which the market will fall, ends up deterring buyers (negative feedback).
- Once the market begins to fall regularly (a bear market), some investors may expect further losing days and refrain from buying (positive feedback), but others may buy because stocks become more and more of a bargain (negative feedback).
The conventional economic equilibrium model of supply and demand supports only ideal linear negative feedback and was heavily criticized by Paul Ormerod in his book "The Death of Economics" which in turn was criticized by traditional economists. This book was part of a change of perspective as economists started to recognise that Chaos Theory applied to nonlinear feedback systems including financial markets.
In biological systems such as organisms, ecosystems, or the biosphere, most parameters must stay under control within a narrow range around a certain optimal level under certain environmental conditions. The deviation of the optimal value of the controlled parameter can result from the changes in internal and external environments. A change of some of the environmental conditions may also require change of that range to change for the system to function. The value of the parameter to maintain is recorded by a reception system and conveyed to a regulation module via an information channel.
Biological systems contain many types of regulatory circuits, among which positive and negative feedbacks. Positive and negative don't imply consequences of the feedback have positive or negative final effect. The negative feedback loop tends to slow down a process, while the positive feedback loop tends to accelerate it.
Feedback and regulation are self related. The negative feedback helps to maintain stability in a system in spite of external changes. It is related to homeostasis. Positive feedback amplifies possibilities of divergences (evolution, change of goals); it is the condition to change, evolution, growth; it gives the system the ability to access new points of equilibrium.
For example, in an organism, most positive feedbacks provide for fast autoexcitation of elements of endocrine and nervous systems (in particular, in stress responses conditions) and play a key role in regulation of morphogenesis, growth, and development of organs, all processes which are in essence a rapid escape from the initial state. Homeostasis is especially visible in the nervous and endocrine systems when considered at organism level.
Feedback is also central to the operations of genes and gene regulatory networks. repressor (see Lac repressor) and activator proteins are used to create genetic operons, which were identified by Francois Jacob and Jacques Monod in 1961 as feedback loops.
In zymology, feedback serves as regulation of activity of an enzyme by its direct product(s) or downstream metabolite(s) in the metabolic pathway.
There is an ice-albedo positive feedback loop whereby melting snow exposes more dark ground (of lower albedo), which in turn absorbs heat and causes more snow to melt. This is part of the evidence of the danger of global warming.
Compare with: feed-forward
As an organization seeks to improve its performance, feedback helps it to make required adjustments.
Examples of feedback in organizations:
- Control theory
- Delayed feedback
- Knowledge of results
- Low-key feedback
- Sensory feedback
- Stability criterion
- Positivity/negativity ratio
- Perverse incentive
- Unintended consequence
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