Editing Detection theory (section)

{{Short description|Means to measure signal processing ability}}
'''Detection theory''' or '''signal detection theory''' is a means to measure the ability to differentiate between information-bearing patterns (called [[Stimulus (psychology)|stimulus]] in living organisms, [[Signal (electronics)|signal]] in machines) and random patterns that distract from the information (called [[Noise (electronics)|noise]], consisting of background stimuli and random activity of the detection machine and of the nervous system of the operator).

In the field of [[electronics]], '''signal recovery''' is the separation of such patterns from a disguising background.<ref name=Wilmshurst>
{{cite book |title=Signal Recovery from Noise in Electronic Instrumentation |author=T. H. Wilmshurst |url=https://books.google.com/books?id=49hfsIPpGwYC&pg=PP11 |pages=11 ''ff'' |isbn=978-0-7503-0058-2 |edition=2nd |publisher=CRC Press |year=1990}}
</ref>

According to the theory, there are a number of determiners of how a detecting system will detect a signal, and where its threshold levels will be. The theory can explain how changing the threshold will affect the ability to discern, often exposing how adapted the system is to the task, purpose or goal at which it is aimed. When the detecting system is a human being, characteristics such as experience, expectations, physiological state (e.g. 
fatigue) and other factors can affect the threshold applied.  For instance, a sentry in wartime might be likely to detect fainter stimuli than the same sentry in peacetime due to a lower criterion, however they might also be more likely to treat innocuous stimuli as a threat.

Much of the early work in detection theory was done by [[radar]] researchers.<ref>{{Cite journal
| pages = 90
| last = Marcum
| first = J. I.
| title = A Statistical Theory of Target Detection by Pulsed Radar
| journal = The Research Memorandum
| access-date = 2009-06-28
| year = 1947
| url = http://www.rand.org/pubs/research_memoranda/RM754/
}}</ref> By 1954, the theory was fully developed on the theoretical side as described by [[W. Wesley Peterson|Peterson]], Birdsall and Fox<ref>{{cite journal |last1=Peterson |first1=W. |last2=Birdsall |first2=T. |last3=Fox |first3=W. |title=The theory of signal detectability |journal=Transactions of the IRE Professional Group on Information Theory |date=September 1954 |volume=4 |issue=4 |pages=171–212 |doi=10.1109/TIT.1954.1057460 }}</ref> and the foundation for the psychological theory was made by Wilson P. Tanner, David M. Green, and [[John A. Swets]], also in 1954.<ref>{{cite journal |last1=Tanner |first1=Wilson P. |last2=Swets |first2=John A. |title=A decision-making theory of visual detection. |journal=Psychological Review |date=1954 |volume=61 |issue=6 |pages=401–409 |doi=10.1037/h0058700 |pmid=13215690 }}</ref>
Detection theory was used in 1966 by John A. Swets and David M. Green for [[psychophysics]].<ref>Swets, J.A. (ed.) (1964) ''Signal detection and recognition by human observers''. New York: Wiley{{page needed|date=July 2019}}</ref> Green and Swets criticized the traditional methods of psychophysics for their inability to discriminate between the real sensitivity of subjects and their (potential) [[response bias]]es.<ref name="Green&Swets">Green, D.M., Swets J.A. (1966) ''Signal Detection Theory and Psychophysics''. New York: Wiley. ({{ISBN|0-471-32420-5}}){{page needed|date=July 2019}}</ref>

Detection theory has applications in many fields such as [[diagnostics]] of any kind, [[quality control]], [[telecommunications]], and [[psychology]].  The concept is similar to the [[signal-to-noise ratio]] used in the sciences and [[confusion matrix|confusion matrices]] used in [[artificial intelligence]]. It is also usable in [[alarm management]], where it is important to separate important events from [[background noise]].