Talk:Feedback

message: is external linking allowed?, in any case much good info in http://prof.usb.ve/williamc/Mejoramiento/historia.html
should be made available here 
in electronics the para are disordered, positive feedback (suject of great Armstrong deForset patent dispute)predates Black's negative feedback amplifier and should be refered to first, PID is a subset of negative feedback control techniques :jcox
---
I don't believe that the explanation of audio feedback is correct. It identifies the frequency of feedback noise as related to the transit time through the system (Implying it's a matter of repeating the waveform, the effect you might get with digital echo or flange). But I'm 95% sure that's completely irrelevant in a system like this, the waveform is completely obliterated by all the transitions made, all you're left with is frequencies that approximate those you started with.
OK, a quick test: I was able to get audible feedback with a 1/2 second delay in the loop, which should give a frequency of 2 hz, 5 octaves below audible.
So I'm rather sure the frequency of feedback is not determined by transit time, but by the frequency response of the whole system. All real world systems contain some capacitance and inductance, meaning they all act as very wide, low, bandpass filters. But when you amplify and feedback the filtered sound into the filtered sound, you've naturally created an oscillator (the simplest forms of analog oscillators work on exactly this principle).
So unless anyone objects I'm going to change the explanation to reflect this.
User:Wji
----
Although feedback was perhaps discovered during the course of the development of electronics, it exists in many natural processes and the word (although not present in earlier dictionaries, for example the original OED) represents a concept in general use outside engineering. Therefore the article should begin with the general concept but include a substantial section on control theory. I was first introduced to feedback during training on servo mechanisms many years ago and am a bit rusty, but I clearly remember it took both positive and negative feedback to make them work. What we call feedback like with a microphone is perhaps not feedback in the sense we are using it here. User:Fredbauder
I agree that there is more than one sense of the word feedback.  The Penguin Dictionary of Electronics, for example, has separate entries for feedback in the general sense and feedback control loop in the specific context of control systems.  The Chambers Science and Technology Dictionary has headings for feedback (acoustic), feedback (telecommunications) and feedback control loop, so perhaps there are really three different concepts.  If we wish to separate the general from the particular, I would suggest the following structure for the Wikipedia (with separate articles for hunting and feedback):
*Hunting (known to mechanical engineers as early as 1880, according to OED2)
*Feedback
**as originally defined, i.e. in electronic amplifiers (see OED2 citation from 1920)
***acoustic feedback in public address amplifiers (OED2 has a 1921 citation of howl) - perhaps this could be a separate article
**feedback theory applied to control loops (probably first applied in World War II)
***control loops in nature, i.e. natural systems that can be analysed with control loop theory (existing since prehistory but only understood by humans in the light of control theory)
Do you think this is reasonable?  Unfortunately it contradicts your idea of putting the natural phenomena first.  My scheme lists things in the order of discovery by man, whereas yours is nature-based.  I cannot say which is better.
As for the microphone example, this is an illustration of feedback in the electronic (or electroacoustic) sense, not in the control loop sense.  The feedback is always positive, because sound from the loudspeakers is always added to, never subtracted from, the sound entering the microphone.  What changes is the loop gain, which varies as the user moves the microphone relative to the speakers.  As soon as the loop gain exceeds unity, the system howls.  This effect is independent of frequency.  I believe that a system with negative feedback can only become unstable if the signal frequency exceeds the bandwidth of the feedback loop.
In control theory you can have multiple feedback paths (often three: proportional, integral and derivative) and it is meaningless to talk about overall positive or negative feedback, because the three paths may have different characteristics.  --Heron
What I suggest is a simple introduction which includes the general case, followed by as much specialized technical information as you feel appropriate. I agree the notion of postive and negative is applicable only to 2 dimensional systems, but I think it should remain in the introduction. I don't think organization around order of discovery is good; I prefer organization to start with a brief general introduction using simple language and concepts followed by (in this case) an engineering section, followed by the ways the concept has been adapted to natural systems. I guess runaway positive feedback is what we are talking about with apmplifiers. Fred Bauder
I divided the article into sections, without changing the words much.  I may go further and remove the acoustic example to a separate article, but I'll leave 'hunting' where it is.  --Heron
----
I have been bold and removed the acoustic feedback section totally. I have linked the existing article at Audio feedback to the disambiguation page. The main differences in the removed section (reproduced below) lacking in the original page are the points about the band-pass filter and the electronic oscillator.
I believe the band-pass filter point is incorrect anyway. True, all systems have some kind low and high pass filter in them, but this is generally well outside the human range of hearing, and in any case, makes no difference to the presence of feedback. The deleted section was also vague as to whether this was affecting the presence or nature of the feedback, but if it were just the latter, there are plenty of other factors involved (at the very least, the inherant EQ of the system would be much more important).
Also, the electronic oscillator point seems slightly amibiguous too, although I could understand if people wanted this link in the main article. It might be worth pointing out that the simplicity is certainly not in the waveform, but in the construction.
--postglock 07:49, 6 Jun 2005 (UTC)
thread_title:  Older comments 

message: postglock- lemme know if my last version works for you. thankz, Ished-out amounts of Vonn-ness 14:19, 10 September 2005 (UTC)
thread_title:  on mention of "[[audio feedback]]"at top 

message: > Feedback is the signal that is looped back to control a system within itself.
The mention of "signal" and "control" seem overly teleological. Here are some definitions of feedback loop from around the net; a definition of feedback ought to work well with these sorts of definitions:
* "A feedback loop is a system where outputs are fed back into the system as inputs, increasing or decreasing effects." (from this wikipedia's "feedback loop" article)
* "a linkage of two or more system components that forms a round-trip flow of information."
* "the output of some process or system is fed back into the system as a partial input, modifying the process."
* "a self-perpetuating mechanism of change and response to that change."
* "A series of actions which affect one another in a way that circles back to the original action."
* "In the climate system a “feedback loop” refers to a pattern of interacting processes where a change in one variable, through interaction with other variables in the system, either reinforces the original process (positive feedback) or suppresses the process (negative feedback)."
* "In a system where a transformation occurs, there are inputs and outputs. ... 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."
What is your favorite, least constraining definition of feedback?
love, raiph 05:11, 10 October 2006 (UTC)
thread_title:  Problems with the current definition of "Feedback" 

message: There's a long laundry list of important theories, phenomena and more built directly on top of feedback loops that aren't mentioned on this page but should, imo, be considered. (I think I could easily list a dozen, and maybe a hundred, but the specifics aren't my point and I really don't want to get into that game yet if we can avoid it.)
Conversely, much of what's on the page right now seems too detailed, even for me, someone who's been intellectually focused on feedback loops for over a decade.
I propose I/we refactor the page. The introduction should be as general as possible. A History section seems a natural. Maybe an Examples section. I see most of the details of particular feedback phenomena going on their own pages.
Comments?
love, raiph 03:44, 3 October 2006 (UTC)
thread_title:  Proposal to refactor content 

message: *Support: It's the same content. Certainly feedback loops are everywhere, so this is in a way a disambiguation page.+mwtoews 21:40, 22 December 2006 (UTC)
thread_title:  Merge [[Feedback loop]] into [[Feedback]] 

message: I am used to finding concise explanations in the first paragraphs of a Wikipedia article, and would propose the following thumbnail sketch of "feedback" for the first para. I haven't edited an article so won't presume, but this example is technically accurate and memorable:
Feedback: an action changes a system and then the system changes the action. Positive feedback increases the action: you step on the brake pedal in a moving car, and the car slows, pushing your foot down harder on the brake. Negative feedback decreases the action: you step on the gas pedal and the car accelerates, pulling your foot off the gas pedal.
If this is appropriate perhaps someone will include it.
68.98.117.241 23:25, 27 January 2007 (UTC)
thread_title:  Content for first paragraph 

message: There is a Rush album called Feedback that should be included in the disambiguation page. --The Fwanksta
:The winning contestant from Who Wants to be a Superhero was called Feedback (Matthew Atherton).  This should be included on the disambiguation page.
:: Feedback is also widely used to refer to suggestions given to people or companies in order to help improve behaviour, services, results or  products. Feedback to students about homework results, to workers about team performance, to companies about product quality and so on. There is literature and research about effective feedback, impact of feedback and so on. It appears that Wikipedia does not have articles about this kind of feedback, other than 360-degree feedback - josei 19:06, 21 August 2007 (UTC)
thread_title: Other Uses of the Word "Feedback" 

message: I removed the tag to split the article because there was no response the last four weeks. - Mdd 19:59, 12 November 2007 (UTC)
replies: text: Sorry, I just ran across this article now.  This definitely needs to be split.  As somebody mentioned above, the only thing linking these things together is a really broad concept of the term "Feedback".  The methods by which feedback occurs within each of these fields - electronics, biology, communication - are really distinct, and feel haphazardly jammed together in one article like this.  Put it this way: nobody is going to be looking for information about "feedback" at such a macroscopic level as to benefit from a one-size-fits-all article like this; they're probably going to be looking for it as it relates to a specific field.  I can take this on as a personal project to split these off and build a worthwhile disambiguation page. Torc2 (talk) 21:57, 28 November 2007 (UTC)
replies: text: Not haphazard, the article header explains it. Feedback is when the output of come process loops around back to become an input to the process. It simply is a broadly applied principle.  —Preceding unsigned comment added by 203.206.220.108 (talk) 10:14, 5 October 2008 (UTC)
thread_title:  Tag to split this article removed 

message: Hello. This article has two references, which is good. I added a "citations missing" tag because most sections have no inline citations and thus there is no way for the reader to know to which of the two refs any particular piece of information is sourced. OK in advance from my point of view to remove or move or change this tag. Best wishes. -Susanlesch 18:43, 12 November 2007 (UTC)
replies: text: Tahnks, I think there are no references at all in this article. So I replaced this tag. - Mdd 20:00, 12 November 2007 (UTC)
replies: text: The concept of "feedback" is such a broad and high level concept that the primary purpose of this article is to provide an overview and to lead the reader to links that get deeper into more specific topics. Since wikipedia provides extensive in-depth details elsewhere, it would be a complete waste of time to replicate a huge list of references here. Please don't be simple minded trying to apply rules about citations, it is of benefit to no one. If there are examples where the information on this page disagrees with other more in-depth articles in Wikipedia then that should be fixed. 10:11, 5 October 2008 (UTC)
thread_title: Citations

message: The example of vacuum advance control in older automotive ignition systems is bogus.
Such systems did not employ any kind of feedback mechanism; i.e., they did not sense
or react to any change they produced.  —Preceding unsigned comment added by 24.22.7.221 (talk) 21:31, 17 January 2008 (UTC)
thread_title:  Bogus examples 

message: The overview starts with the following sentence:
* Feedback is both a mechanism, process and signal that is looped back to control a system within itself
both is followed by three items instead of two. Hence, both should be removed. [Georg]  —Preceding unsigned comment added by 206.113.192.12 (talk) 17:04, 25 January 2008 (UTC)
replies: text: Ok, go ahead. -- Mdd (talk) 21:56, 25 January 2008 (UTC)
thread_title:  Incorrect sentence 

message: This seems confusing. How can feedback be both positive and negative at the same time? These are exclusive, surely. If this means a switching function, where the feedback changes between positive and negative, then the definition should clarify this. If it means a balancing, then two feedback loops must be involved (one positive, one negative.)I have searched several online sources, and they all seem to cite each other (including this one) but I can't find an original definition. I have noted several references to "bipolar feedback transistors", but suspect that means a feedback loop involving a bipolar transistor, rather than "bipolar feedback" involving a transistor.If bipolar feedback is present in many systems, can someone provide an example?
Trevithj (talk) 02:43, 10 September 2008 (UTC)
thread_title:  Bipolar feedback 

message: The subsection "In electronic engineering" re-explains the concepts of negative feedback and positive feedback, which are not particularly specific to electronic engineering. Anyway, the section that contains this subsection is "Applications" so this is not the right place for explaining a general principle.
203.206.220.108 (talk) 01:28, 8 November 2008 (UTC)
thread_title:  In electronic engineering 

message: *3 - the feedback signal does not change when the input signal changes, in which case there is no feedback.  This is known as a Linear system.
If no feedback is an example of feedback then sitting on your bum is an example of flying. In addition linear systems can have feedback, and non-linear systems do not require feedback. Thus the above should be deleted. 203.206.220.108 (talk) 12:31, 28 December 2009 (UTC)
replies: text: Bad example, When everytime I've been on an airplane, I was sitting on my bum.  —Preceding unsigned comment added by RaptorHunter (talk • contribs) 02:37, 21 November 2010 (UTC)
thread_title:  Feedback equals No Feedback 

message: This article has the same naming problem that correlation article had years ago.  People at first mislabeled correlation as positive and negative.  That is nebulous.  It was correctly changed to direct and inverse correlation.  
This article suffers from the same issue.  It should NOT be positive and negative feedback.  Instead the proper more accurate terms are converging and expanding feedback.  The article needs renamed as well.
173.188.7.24 (talk) 21:19, 4 March 2012 (UTC)
replies: text: Please provide sources for the terms "expanding feedback" and "converging feedback" and why they are more applicable than the traditional terms, positive and negative feedback. Jojalozzo 22:10, 4 March 2012 (UTC)

text: May I suggest that the terms "reinforcing loop" and "balancing loop" are used more often to avoid the ambiguity of the terms "positive" and "negative" (and even "feedback"). See for example the work of John Sterman and Peter Senge, and Systems dynamics or Causal loop diagram. Trevithj (talk) 03:18, 7 March 2012 (UTC)
replies: text: They could be mentioned, but probably not "used more", since they aren't the terms most commonly used in discussion of feedback.  Dicklyon (talk) 07:11, 7 March 2012 (UTC)
replies: text: That may be true, but I submit that "reinforcing loop" is a less ambiguous term than "positive feedback". Both "positive" and "feedback" have (by my count) three distinct meanings, so the common term could refer to "desirable speaker-howl", "beneficial appraisal" or "increasing criticism", to name a few. Trevithj (talk) 01:51, 8 March 2012 (UTC)
thread_title: This article suffers from vagueness

message: I see a need to make this section:
*more generic. The current overview emphasises the cybernetic/electronic sense, jumps too quickly into definitions of positive/negative, and assumes a mechanism of control that is largely specific to electronics (output used to influence input). Feedback doesn't always involve measuring 'output', and not all mechanisms influence 'input'. (Ramaprasad, 1983)
*more about the origin of the term. The paragraphs on feedforward seem to be trying to do this, but don't define feedforward clearly (with citations). Also other authors use 'feedforward' in a different way to this (e.g., Hendry 1988), which is confusing.
I propose: describing the history of the term "feed-back", and show its adoption from verb phrase to noun; moving the examples to their relevant sections in Applications, where they can be explained in greater detail; removing the description of positive/negative types, since these are already covered later in the article - and have their own pages anyway. --Trevithj (talk) 22:09, 29 March 2012 (UTC)
thread_title: Tidying the Overview

message: Any objections if I remove the Audio feedback and Performance appraisal sections in the lead? They aren't really in the right context here, and are already covered in the disambiguation page and the "See also" list. --Trevithj (talk) 00:43, 18 April 2012 (UTC)
thread_title:  Remove redundant synonyms 

message: Is email administration really a social science? Maybe in the 90's it was, but we must have passed that stage.  — Preceding unsigned comment added by 14.200.55.92 (talk) 08:08, 30 November 2013 (UTC)
thread_title:  Email and social science 

message: The "Types of Feedback" section was poorly written, and jumped immediately to a rather unclear discussion on the social-science meaning of the words "positive feedback" and "negative feedback".  I've tried to rewrite it to make it a bit clearer.  Geoffrey.landis (talk) 16:12, 27 June 2014 (UTC)
replies: text: I don't question your intentions. However, the terms "positive" and "negative" are ambiguous terms, and the previous version reflected this. It didn't say anything about social science - in fact the quoted definitions come from behavioral and management science. So now one context is assumed, and the other is rather narrowly labeled almost as an afterthought, whereas before they were given a more equal weighting. New version isn't really clearer. Trevithj (talk) 09:20, 28 June 2014 (UTC)

text: However, your approach in moving the discussion on conflicting definitions out of the discussion of types does make sense. I have generalized the sub-heading (it may well be a social-science phenom, but citations are required.) Sorry if my edit-reversal was too precipitous. Trevithj (talk) 21:46, 2 July 2014 (UTC)
replies: text: the "types of feedback" section is still rather poorly written. "the altering of the gap between reference and actual values of a parameter, based on whether the gap is widening (positive) or narrowing (negative)" may be technically accurate, but it is nearly incomprehensible to anybody who doesn't already know what feedback is. Geoffrey.landis (talk) 17:20, 10 August 2014 (UTC)
thread_title:  Types of feedback 

message: The current definition used in the article to scope it is:
:Feedback is a process in which information about the past or the present influences the same phenomenon in the present or future.
The issue I have with this is that it doesn't map well onto many feedback loops. For example a ball-cock/float valve does not communicate information in any normal sense, it physically closes the valve. Another example is climate, there are feedback loops on the rainfall and temperature that go via bacteria seeding clouds. These are not information in any normal sense. Information is usually considered as a trigger to action, whereas these are mechanical feedback loops that physically force negative feedback.
Additionally there is the question of what the 'same' phenomenon means; it could mean practically anything.
I propose to change it to:
:Feedback is any process in which the state of a system influences the future state of that system via a closed causal loop.
This is slightly more abstract, but the concept of the 'state of the system' is fully general, as is the term 'influence' and the notion of the loop being closed and causal. These seem to be wider than the current definition and the minimum necessary ingredients for feedback to be said to occur.
I welcome comments.GliderMaven (talk) 16:10, 10 August 2014 (UTC)
replies: text: I think that making up abstract definitions without showing support for them in sources is not likely to get us anywhere.  And I think your definition is too general, in that the state of a system almost always has a causal influence on future state and output, whether there is something identifiable as feedback or not. The previous definition has the same problem, assuming you interpret information broadly enough for it to mean anything.  Dicklyon (talk) 16:53, 10 August 2014 (UTC)
replies: text: In a ball-cock valve, the "ball" is a device which measures the amount of water in the tank. This information is fed (via a mechanical connection) to the valve, the device which controls the rate at which water flows to the tank.  In modern times, the idea that information can be fed via a mechanical connection seems old-fashioned, but it's still feedback. Geoffrey.landis (talk) 17:17, 10 August 2014 (UTC)
replies: text: Unless you are getting into quantum mechanics, which I don't think we are, information is a human thing, whereas the actual feedback is a mechanical or electrical or chemical causal connection.GliderMaven (talk) 18:52, 10 August 2014 (UTC)

text: On the contrary, this is very often misunderstood, and you have done so. The first few sentences of the lead is the part where we state what the editors are considering to be the scope of the article for the readers; what is, and is not in scope is firmly an editorial decision. It cannot be found in any reference at all.GliderMaven (talk) 18:48, 10 August 2014 (UTC)
replies: text: Well, I doubt you believe the intro is open to wild imaginings. Such invention is constrained where definitions are involved by citing supporting sources, a common practice on WP that does not interfere in any way with the purpose of an intro. However, if you object, then provide the sources on this talk page so editors can assess that your proposed definition is indeed consistent with a balanced view of published reliable opinion, and is not a poorly worded approximation. If editors find your sources provide good support, they can decide whether to cite them in the lede or not. Brews ohare (talk) 19:24, 10 August 2014 (UTC)
replies: text: That's basically what I'm doing here, in marked contrast to what you seem to be up to- which is forcing some randomly chosen definitions references on Wikipedia. The point is that the editors, particularly with the wider scoped, more general articles such as this one, end up having to synthesise an umbrella definition that encompasses all of the other definitions (or most of them, some definitions when you look at them hard enough are simply incorrect; dealing with incorrect reference information is something else that Wikipedia editors have to deal with.)GliderMaven (talk) 14:17, 12 August 2014 (UTC)
thread_title:  Definition appears to be over narrow, propose new definition 

message: At present, the lede states:
:"The term "feedback" in this sense is also used as an abbreviation for:
:* Negative feedback – when the fed-back information acts to control or regulate a system by opposing changes in the output or measurement.
This definition of negative feedback suggests that it is an event that occurs when the fed-back information acts. The idea that negative feedback refers to an 'event' seems awkward to me because it emphasizes a transient behavior, rather than the consequence of a particular arrangement or set-up. I am also disturbed by the notion of information as an agent that can 'act'. 
Some sources refer to negative feedback as a process.1 2 3 or as a form of control,4, or as a particular circumstance.5.
That suggests this change:
:"The term "feedback" in this sense is also used as an abbreviation for:
:* Negative feedback – a process in which the fed-back information acts to control or regulate a system by opposing changes in the output or measurement.1
::Sources
::1
Of course, a different reference could be chosen. Brews ohare (talk) 17:25, 27 September 2014 (UTC)
replies: text: There being no discussion here, I implemented this change with two additional references. Brews ohare (talk) 15:29, 29 September 2014 (UTC)
thread_title:  Negative feedback definition 

message: This edit removed extensive sections dealing with educational and other aspects of feedback without providing any feedback here on the Talk page. The in-line editorial comment was made regarding the educational material that article is not about individual uses of feedback, it is about feedback loops; the entire loop- and in quantitative science, and about the social science material removed the most egregious examples and unreferenced material. 
No doubt, some changes were warranted. However, some discussion also is warranted. In particular, the idea that this article should be restricted to "quantitative science" is rather debatable, particularly because cybernetics arose in this context. 
There appears to be a prejudice here that 'feedback' in other areas is used only in the everyday sense of rejection and unfavorable comment. However, that is not the case. Material where feedback is used to imply a detailed critique aimed at modifying a process or organization seems to me an appropriate topic for this article. While overlap will occur with the subjects of Reinforcement or "operant conditioning", and Reinforcement learning, the more technical aspects of feedback are mentioned in these fields and this article could usefully include some subsections that briefly make these connections.  Brews ohare (talk) 17:56, 27 September 2014 (UTC)
replies: text: Whether they're formally types of feedback or not, they're still firmly and clearly forms of reinforcement; if you want to cover them, you should cover them in the most relevant article, which this article isn't.GliderMaven (talk) 16:02, 28 September 2014 (UTC)
thread_title:  Deletion of large sections on feedback in education, management etc. 

message: The lead sentence reads:
:"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.[2]
::Source
:::[2] United States Naval Academy, "Elements of Feedback Control", Chapter 3, Fundamentals of Naval Weapons Systems (accessed August 29, 2014)
Presumably this source is meant to support the 'chain of cause-and-effect' claim. However, this idea does not show up in this source. The word 'chain' and the words 'cause' and 'effect' do not appear in this source. An alternative source is:
:
This source states:
:"This chapter describes causal loop diagrams to portray the information feedback at work in a system. The word causal refers to cause-and-effect relationships. The word loop refers to a closed chain of cause and effect that creates the feedback."
A bit disconcerting for the lede is that Ford restricts the 'chain of cause-and-effect' to a particular type of feedback, namely information feedback, and suggests that the 'chain of cause-and-effect' is not actually the feedback (which is the information, of course) but the mechanism that creates the feedback. 
My suggestion is that the Ford source replace the present source that has nothing to do with the lead sentence, and that some thought be given as to what is the feedback and what is the feedback mechanism.1 2 3 4 5 Brews ohare (talk) 15:19, 30 September 2014 (UTC)
replies: text: That's Norbert Wiener's 1965 definition from his cybernetics work.  It's not bad, but also not very used in engineering.  Dicklyon (talk) 16:41, 30 September 2014 (UTC)

text: I've replaced the Naval Academy source with Ford for the reasons given above, there being no objections raised here. Brews ohare (talk) 12:13, 1 October 2014 (UTC)

text: I've interchanged the first two sentences of the lede because the second sentence provides the definition of feedback and the first sentence describes its implementation. The reverse order is more logical and clearer. Both sentences are now solidly sourced. Brews ohare (talk) 13:07, 1 October 2014 (UTC)
replies: text: It's not a particularly useful or clarifying definition.  I agree with the revert of it.  The figure was also not so useful; what source motivated that one?  And what source motivates distinguishing between feedback and the way feedback is arranged for, the feedback mechanism?  Is distinguishing these better than claiming they are synonyms?  Or is "mechanism" essentially a meaningless term in typical uses?  Dicklyon (talk) 17:49, 1 October 2014 (UTC)
thread_title:  Source supporting lead sentence 

message: The version of the lede installed by GliderMaven with Dicklyon's blessing has the demerits of containing no definition of 'feedback' (it states, not what it is in fact, but only circumstances attending its appearance - it 'occurs when...' ), and of ignoring the role of information pointed out by a seminal source (Wiener) and adopted by many subsequent authors. The present lede  employs a source focused upon information (Ford) without benefiting from its teachings. This version removed by GliderMaven has none of these defects and is more completely sourced.  Brews ohare (talk) 14:34, 2 October 2014 (UTC)
replies: text: Apparently the only changes to the lede are the addition of links to two seemingly opposing sources. Ford suggests that feedback is a causal loop, while Aström & Murray point out that in a simple feedback loop it is impossible to say whether part A is a cause acting on part B or vice versa as each affects the other. Probably Ford would agree that a "casual loop" is inherently ambiguous in this way, although he has no hesitation in calling part A a cause acting on part B, and ignores the fact that part B influenced the cause provided by part A  via part B’s own action.  For more complex systems, feedback may not be a loop of any kind, of course, as pointed out by Ashby, p. 54 who goes so far as to say the concept of feedback "becomes artificial and of little use when the interconnections between the parts become more complex". In any event the present substitution of some circumstances where feedback might occur (Feedback occurs when ...), instead of what the lede needs, namely a definition of what feedback actually is, has not been addressed. Brews ohare (talk) 18:21, 11 November 2014 (UTC)
thread_title: Inadequacies of the present lede

message: This article is poorly written and it's not concise. The introduction is lousy and it does not list positive feedback so I wonder why only negative feedback should be listed. The section on terminology implies two confusing definitions and later, in the electronic engineering section, a third definition based on direction is included. Later, in the negative feedback loops section, a definition based on phase is introduced. In my opinion, the definition in terms of direction and phase are confusing or even incorrect. Also, if multivibrators are a form of positive feedback, they should be listed under the positive feedback section. Oscillators are presented and my understanding is that they use positive feedback. This is not explained or mentioned at all. Lastly, as far as I know, latches use positive feedback. This is not state anywhere in the article. Nothing is mentioned about flip-flops either. Both oscillators and latches/flip-flops should be listed under their respective categories. This article needs a huge rework.
ICE77 (talk) 16:50, 14 June 2015 (UTC)
thread_title:  Poorly written article 

message: > A negative feedback loop is one that tends to slow down a process, whereas the positive feedback loop tends to accelerate it.
This sentence is capable of being completely misunderstood, seemingly supporting a common misunderstanding in certain fields of biology, namely that systems possessing a positive feedback tend to respond faster, and systems possessing a negative feedback tend to respond slower.
The problem arises because it is not stated at all as compared to what exactly a "negative feedback [..] tends to slow down a process". That is: given a process with a positive or negative feedback loop, how does the corresponding process without the feedback loop exactly looks like? This is very problematic because in a very common way to answer this question, rather the direct opposite of the statement above holds.
Example:
Consider the linear system
\displaystyle \frac{d}{dt}x(t)=(1-k)(u(t)-x(t)), x(0)=0
where 0<k<1 corresponds to a positive feedback of "strength" k, k<0 to a negative feedback of "strength" -k, and k=0 to "no feedback".
Consider the input u(t) switching from zero to one at t=0. The solution is \displaystyle x(t)=1-e^{(1-k)t}, and the time constant is \displaystyle T=\frac{1}{1-k}. That is, a positive feedback (k>0) increases the time constant (makes the system slower), and a negative feedback (k<0) decreases the time constant (makes it faster).
I propose to completely delete the statement rather than keeping it in its current form.  — Preceding unsigned comment added by Langmo (talk • contribs) 12:50, 22 February 2017 (UTC)
thread_title:  Response speed positive/negative feedback in Biology section 

message: this article/ subject matter & its related concepts- are they more closely associated with life sciences or with engineered systems? can anyone estimate a proportion break-down, like a percentage that it pertains to each? 
leaving this question unanswered will leave the article muddled and possibly confusing, depending on the initial assumptions of the reader. skakEL 19:41, 9 July 2020 (UTC)
thread_title:  life sciences & engineered systems - what' the breakdown?   50/50?  90/10?  

message: Op-amp with nagative positive feedback 2402:3A80:16E1:87D:0:3B:122A:2A01 (talk) 08:57, 22 February 2022 (UTC)
replies: text: @ 159.192.43.62 (talk) 14:20, 13 January 2024 (UTC)
thread_title:  Medical electronic 3330303