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This nOde last updated February 26th, 2004 and is permanently morphing...
(7 Cauac (Rain) / 7 K'ayab (Turtle) 69/260 - 12.19.11.0.19)
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feedback
feedback (fêd´bàk´)
noun
1. a. The return of a portion
of the output of a process
or system to the input, especially when used to maintain performance or
to control a system or process. b. The portion of the output so returned.
2. The return of information
about the result of a process or activity; an evaluative response: asked
the students for feedback on the new curriculum.
According to cybernetics, the human brain and nervous system coordinate information to determine which actions will be performed; control mechanisms for self-correction in machines serve a similar purpose. This principle, known as feedback, is the fundamental concept of automation. One of the basic tenets of cybernetics is that information can be statistically measured in accordance with the laws of probability. Purposive behavior in humans or in machines requires control mechanisms that maintain order by counteracting the natural tendency toward disorganization.
In a system where a transformation occurs, there are inputs and outputs. The inputs are the result of the environment's influence on the system, and the outputs are the influence of the system on the environment. Input and output are separated by a duration of time, as in before and after, or past and present.
there's a neat little video trick that's commonly
known. point your camcorder at a television set connected to the camera,
and play with the zoom and angles and lighting.
eventually you'll fall into some sort of strange loop that is very psychedelic.
a fractal
wormhole
of sorts. i had plenty of fun with this coming down off of acid
a couple of times. - @Om*
12/3/99
give feedback re: fUSION Anomaly
by emailing me.
"...in perfecting feedback and the
means of rapid data manipulation, the science
of cybernetics
was gaining a deeper understanding of life itself
as being, at its core, the processing
of information."
- Theodore Roszak, _The Cult of Information_
Jimi
Hendrix and his use of feedback and distortion.ambient
space rock track _Guitar Feedback Manipulation_ MP3
by Experimental Audio Research off of _Mesmerised_
on Sympathy For The Record Industry (1994)Anomalog:
How
The Internet Invented Howard Dean Daybreak topped off my mug with
more tea.
"When the Buddha spoke of control, he wasn't talking about
clamping down on our urges, but about cultivating a homeostatic sense of feedback,
an ethics of constant modulation. Shakyamuni
once compared meditation to a musician constantly tuning a string that keeps
going flat or sharp. That's the trick—constant
negative feedback. A Buddhist gun-freak I knew likens zazen
to the flight of F-14s, which are aerodynamically
unstable. Computers must constantly adjust the surfaces of the plane's wings
and fuselage in response to atmospheric conditions in order to keep the plane
aloft. That's the Middle Way. The trap is the vicious escalation of positive
feedback, whether it's a barfight or the arms race or consumer culture. For
Buddhists, satisfying ordinary desires is like a thirsty man drinking sea-water.
More positive feedback. But what if we introduce
a minus sign into the loop? What if we become the minus sign? Rather than respond
to anger with more anger, what if can realize
that there is no human being there to be angry at, just the resonance
of countless molecular machines producing
the complexity of life?"
- selections from the notebooks
of Lance Daybreak, curated by Erik Davis in _Shards Of The Diamond Matrix_
"We shape our tools and thereafter
they shape us." - Marshall
McLuhan
 |
"It is my thesis that the physical functioning of
the living individual and the operation of some of the newer communication
machines are precisely parallel in their analogous attempts to control
entropy through feedback." - Norbert
Wiener
 |
 |
In every feedback loop, as
the name suggests, information
about the result of a transformation or an action is sent back to the input
of the system in the form of input data. If these new data facilitate and
accelerate the transformation in the same direction as the preceding results,
they are positive feedback - their effects are cumulative. If the new data
produce a result in the opposite direction to previous results, they are
negative feedback - their effects stabilize the system. In the first case
there is exponential growth or decline; in the second there is maintenance
of the equilibrium.
 |
Positive feedback leads to
divergent behavior: indefinite expansion or explosion (a running away toward infinity)
or total blocking of activities (a running away toward zero).
Each plus involves another plus; there is a snowball effect. The examples
are numerous: chain reaction, population explosion, industrial expansion,
capital invested at compound interest, inflation, proliferation of cancer
cells. However, when minus leads to another minus, events come to a standstill.
Typical examples are bankruptcy and economic depression.
 |
In either case a positive feedback loop left to
itself can lead only to the destruction of the system, through explosion
or through the blocking of all its functions. The wild behavior of positive loops
- a veritable death wish - must be controlled by negative loops. This control
is essential for a system to maintain itself in the course of time.
Negative feedback leads to
adaptive, or goal-seeking behavior: sustaining the same level, temperature,
concentration, speed, direction. In some cases the goal is self-determined
and is preserved in the face of evolution:
the system has produced its own purpose (to maintain, for example, the
composition of the air or the oceans in the ecosystem or the concentration
of glucose in the blood). In other cases man has determined the goals of
the machines (automats and servomechanisms). In a negative loop every variation
toward a plus triggers a correction toward the minus, and vice versa. There
is tight control; the system oscillates
around an ideal equilibrium that it never attains. A thermostat or a water
tank equipped with a float are simple examples of regulation by negative
feedback.
 |
Peter Jackson echoes the sentiment,
but he also feels that the intense
feedback enabled by the Internet
is worthwhile. "Fans have so much information and communicate about films for
so long that it will hopefully force filmmakers to make much better movies.
The voice of the audience is heard: They don't want crap."
- Erik Davis - _The Fellowship Of
The Ring_ in _Wired_
9.10 - October 2001
re: J.R.R.
Tolkien
In engineering, economics and biology, feedback is a process
whereby some proportion of the output signal of a system is fed back to the
input, in order to change the dynamic behaviour of the system.
Feedback may be negative, thus tending to reduce output,
or positive, thus increasing 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.
Feedback in electronic engineering
Feedback is designed into many electronic and other technical devices.
In engineering control theory, feedback is a process in which a signal generated from the output of a system is applied as an input to the same system.
The most common general-purpose controller is a proportional-integral-derivative
controller. Each term of the PID controller copes with time.
The proportional term handles the present state of the system, the integral
term handles its past, and the derivative or slope term tries to predict and
handle the future.
If the signal is inverted on its way round the control
loop,
the system is said to have negative feedback; otherwise, the feedback is said
to be positive. Negative feedback is often deliberately introduced to increase
the stability and accuracy of a system, as in the feedback amplifier invented
by Harold Stephen Black. This scheme can fail if the input changes faster than
the system can respond to it. When this happens, the negative feedback signal
begins to act as positive feedback, causing the output to oscillate or hunt.
Positive feedback is usually an unwanted consequence of system behaviour.
A well-known example of runaway positive feedback in electronic
systems is called "howl" or "howl-round". This occurs in
public address systems when sound from the loudspeakers reaches the microphone,
is amplified by the system, and is then fed back into the system at even higher
volume. All electrical
systems contain capacitance and inductance and so act as band-pass filters
responding better to certain frequencies.
In a single loop through the system, this effect is negligible, but it becomes
severe when the signal passes through the system repeatedly. This effect is
the basis of the simplest kinds of analogue electrical oscillator.
With mechanical devices, hunting can be severe enough to destroy the device.
Feedback in economics
A system prone to hunting is the stock market, which has both positive and negative feedback mechanisms. 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, deter 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).
Feedback in nature
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 and activator proteins are used to create genetic operons, which were
identified by Francois Jacob and Jacques Monod in 1961 as feedback loops.
Any self-regulating natural process involves feedback and is prone to hunting. A well known example in ecology, is the oscillation of the population of snowshoe hares due to predation from lynxes.
Compare with: feed-forward
Feedback in organizations
As an organization seeks to improve its performance, feedback helps it to make required adjustments.
Examples of feedback in organizations:
* Financial audit
* performance appraisal
* shareholder meetings
* customer surveys
604
track _Eternal Feedback_ MP3 (160k)
by Vibrasphere off of _Echo_ on Spiral Trax (2000)/Soul
Ham_ 12" by Adrenochrome on Plastik Park (2001)
by Lotion off of _Telephone
Album_ on spinART
(1998)
by Pete Namlook & Atom Heart off of _Jet Chamber_ CD on FAX (1995)
by Keith Fullerton Whitman off of _Playthroughs_ CD on Kranky #055 (2002)InterfaceLight_
MP3 (vK)
off of _EVOLution_
CD on Metropolis #142 (1998)_Immortal_
MP3 (192k)
off of _Mechanical Horizon_ CD on Metropolis (2000)
by Tobias Schmidt off of _The Finger Print ep_ 12" on Mosquito #006 (1996)ambient
track _Super Feedbacker_ MP3
by Fennesz off of _Hote Paral.lel_ on Mego (1997)Silence_
MP3 (192k)
by Decoded Feedback off of _Mechanical Horizon_ on Metropolis (2000)
by Massive Attack vs. Mad Professor
by Chrome off of _Half Machine Lip Moves/Alien
Soundtracks_ CD
on Touch & Go
(1978/1979/1990) |
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