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==History==
PCT has roots in the 19th-century physiological insights of [[Claude Bernard]] and in 20ththe 20th-century inresearch of Peter Putnam<ref name="Gefter 2025">{{cite web | last=Gefter | first=Amanda | title=Finding Peter Putnam | website=Nautilus | date=June 17, 2025 | url=https://nautil.us/finding-peter-putnam-1218035/ | access-date=June 18, 2025}}</ref><ref name="Putnam Fuller 1964">{{cite web | title=Outline of a Functional Model of the researchNervous bySystem, [[WalterPutnam/Fuller Bradford1964 Cannon|Walterfirst1=Peter|last1=Putnam|last2=Fuller|first2=Robert| Bwebsite=The Peter Putnam Papers | date=October 30, 1970 | url=https://www.peterputnam.org/outline-of-a-functional-model-of-the-nervous-system-putnam/fuller-1964 | access-date=June 18, 2025}}</ref> and [[Walter Bradford Cannon]], and in the fields of [[control systems engineering]] and [[cybernetics]]. Classical negative feedback control was worked out by engineers in the 1930s and 1940s,<ref name="black93">Harold Black and the Negative-Feedback Amplifier, Ronald Kline, IEEE Control Systems Magazine, Aug 1993, Volume 13, Issue 4, Pages 82-85</ref><ref name=Bennett>{{cite journal | last =Bennett | first =Stuart | title =A brief history of automatic control | journal =IEEE Control Systems Magazine | volume =16 | issue =3 | pages =17–25 | date =June 1996 | url =http://ieeecss.org/CSM/library/1996/june1996/02-HistoryofAutoCtrl.pdf | doi =10.1109/37.506394 | access-date =18 July 2016 | archive-url =https://web.archive.org/web/20160809050823/http://ieeecss.org/CSM/library/1996/june1996/02-HistoryofAutoCtrl.pdf | archive-date =9 August 2016 | url-status =dead }}</ref> and further developed by [[Norbert Wiener|Wiener]],<ref name=Wiener48>{{cite book | title =Cybernetics: Or Control and Communication in the Animal and the Machine | publisher =Hermann & Cie | date =1948 | ___location =Paris }} 2nd revised ed. 1961, MIT Press, Cambridge, MA. {{ISBN|978-0-262-73009-9}}.</ref> [[William Ross Ashby|Ashby]],<ref name=Ashby.DFB>{{cite book | last =Ashby | first =William Ross | title =Design for a Brain | publisher =Chapman & Hall | date =1952 | ___location =London | url =https://archive.org/details/designforbrainor00ashb }}</ref> and others in the early development of the field of [[cybernetics]]. Beginning in the 1950s, [[William T. Powers]] applied the concepts and methods of engineered control systems to biological control systems, and developed the experimental methodology of PCT.<ref name=Runkel.cast>{{cite book | last =Runkel | first =Philip J. | title =Casting nets and testing specimens: Two grand methods of psychology | publisher =Praeger | date =1990 | ___location =New York | page =103 | isbn =978-0-275-93533-7 }}</ref><ref name=Cziko.TWD>{{Citation | last =Cziko | first =Gary | title =The things we do: Using the lessons of Bernard and Darwin to understand the what, how, and why of our behavior | place =Cambridge, MA | publisher =MIT Press | year =2000 | page =[https://archive.org/details/thingswedousingl0000czik/page/9 9] | isbn =978-0-262-03277-3 | url =https://archive.org/details/thingswedousingl0000czik/page/9 }}</ref>
A key insight of PCT is that the controlled variable is not the output of the system (the behavioral actions), but its input, that is, a sensed and transformed function of some state of the environment that the control system's output can affect. Because these sensed and transformed inputs may appear as consciously perceived aspects of the environment, Powers labelled the controlled variable "perception". The theory came to be known as "Perceptual Control Theory" or PCT rather than "Control Theory Applied to Psychology" because control theorists often assert or assume that it is the system's output that is controlled.<ref name=Astrom>{{cite book | last1 =Astrom | first1 =Karl J. | last2 =Murray | first2 =Richard M. | title =Feedback Systems: An Introduction for Scientists and Engineers | publisher =Princeton University Press | date =2008 | url =http://www.cds.caltech.edu/~murray/books/AM08/pdf/am08-complete_28Sep12.pdf | isbn =978-0-691-13576-2 }}</ref> In PCT it is the internal representation of the state of some variable in the environment—a "perception" in everyday language—that is controlled.<ref>For additional information about the history of PCT, see:
==Robotics==
PCT has significant implications for Robotics and Artificial Intelligence. W.T. Powers introduced the application of PCT to robotics in 1978, early in the availability of home computers.<ref>{{cite magazine |last=Powers |first=William T. |date=1978 |title=The Nature of Robots: Part I: Defining Behavior |url=http://www.livingcontrolsystems.com/appendixes/byte_june_1979.pdf |url-status=dead |magazine=Byte: The Small Systems Journal |___location=Peterborough, NH |publisher=McGraw-Hill |issue=4 |pages=132-144132–144 |archive-url=https://web.archive.org/web/20070604100935/http://www.livingcontrolsystems.com/appendixes/byte_june_1979.pdf |archive-date=June 4, 2007 |access-date=}}</ref>
<ref>{{cite magazine |last=Powers |first=William T. |date=1978 |title=The Nature of Robots: Part II: Simulated Control Systems |url=http://www.livingcontrolsystems.com/appendixes/byte_july_1979.pdf |url-status=dead |magazine=Byte: The Small Systems Journal |___location=Peterborough, NH |publisher=McGraw-Hill |issue=4 |pages=134-152134–152 |archive-url=https://web.archive.org/web/20070604100935/http://www.livingcontrolsystems.com/appendixes/byte_july_1979.pdf |archive-date=June 4, 2007 |access-date=}}</ref>
<ref>{{cite magazine |last=Powers |first=William T. |date=1978 |title=The Nature of Robots: Part III: A closer look at human behavior |url=http://www.livingcontrolsystems.com/appendixes/byte_aug_1979.pdf |url-status=dead |magazine=Byte: The Small Systems Journal |___location=Peterborough, NH |publisher=McGraw-Hill |issue=4 |pages=94-11694–116 |archive-url=https://web.archive.org/web/20070604100935/http://www.livingcontrolsystems.com/appendixes/byte_aug_1979.pdf" |archive-date=June 4, 2007 |access-date=}}</ref>
<ref>{{cite magazine |last=Powers |first=William T. |date=1978 |title=The Nature of Robots: Part IV: Looking for controlled variables |url=http://www.livingcontrolsystems.com/appendixes/byte_sep_1979.pdf |url-status=dead |magazine=Byte: The Small Systems Journal |___location=Peterborough, NH |publisher=McGraw-Hill |issue=4 |pages=96-11296–112 |archive-url=https://web.archive.org/web/20070604100935/http://www.livingcontrolsystems.com/appendixes/byte_sep_1979.pdf |archive-date=June 4, 2007 |access-date=}}</ref> The comparatively simple architecture,<ref name=Young2017>{{cite journal | last =Young| first =Rupert | author-link = | title =A General Architecture for Robotics Systems: A Perception-Based Approach to Artificial Life. | journal =Artificial Life| volume =23 | issue =2 | pages =236–286 | date =Jun 2017 | access-date = | doi =10.1162/ARTL_a_00229 | pmid =28513206 }}</ref> a hierarchy of perceptual controllers, has no need for complex models of the external world, inverse kinematics, or computation from input-output mappings. Traditional approaches to robotics generally depend upon the computation of actions in a constrained environment. Robots designed this way are inflexible and clumsy, unable to cope with the dynamic nature of the real world. PCT robots inherently resist and counter the chaotic, unpredictable disturbances to their controlled inputs which occur in an unconstrained environment. The PCT robotics architecture has recently been applied to a number of real-world robotic systems including robotic rovers,<ref>
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