The law presently known as 'steering law' in the context of human-computer interaction was originally discovered (theoretically and empirically) by famous HF & E practitioner C.G. Drury, back in 1971 for linear paths and later on to curved paths.
Pointing at stationary targets such as buttons, windows, images, menu items, and controls on computer displays is commonplace and has a well-established modeling tool for analysis - [[Fitts's law|Fitt's law]] (Fitts, 1954) - which states that the time to make an aimed movement (MT) is a linear function of the index of difficulty of the movement: '''''MT = a + bID'''''. The index of difficulty (ID) for any given movement is a function of the ratio of distance to the target (D) and width of the target (W): '''''ID =''''' '''log<sub>2</sub>''(2D/W) -''''' a relationship derivable from [[information theory]].<ref name=":1" /> Fitt's law is actually responsible for the ubiquity of the computer [[Mouse (computing)|mouse]], due to the research of Card, English, and Burr (1978). Extensions of Fitt's law also apply to pointing at spatially moving targets, via the ''[[steering law]]'' (, originally discovered by C.G. Drury in 1971<ref>{{Cite journal|last=DRURY|first=C. G.|date=1971-03-01|title=Movements with Lateral Constraint|url=http://dx.doi.org/10.1080/00140137108931246|journal=Ergonomics|volume=14|issue=2|pages=293–305|doi=10.1080/00140137108931246|issn=0014-0139|pmid=5093722}}</ref> <ref>{{Cite journal|last=Drury|first=C. G.|last2=Daniels|first2=E. B.|date=1975-07-01|title=Performance Limitations in Laterally Constrained Movements|url=http://dx.doi.org/10.1080/00140137508931472|journal=Ergonomics|volume=18|issue=4|pages=389–395|doi=10.1080/00140137508931472|issn=0014-0139}}</ref><ref>{{Cite web|url=http://ieeexplore.ieee.org/abstract/document/4309061/?reload=true|title=Self-Paced Path Control as an Optimization Task - IEEE Xplore Document|website=ieeexplore.ieee.org|language=en-US|access-date=2017-03-02}}</ref>and later on rediscovered in the context of human-computer interaction by Accott & Zhai, (1997, 1999)<ref>{{Cite journal|last=Accot|first=Johnny|last2=Zhai|first2=Shumin|date=1997-01-01|title=Beyond Fitts' Law: Models for Trajectory-based HCI Tasks|url=http://doi.acm.org/10.1145/258549.258760|journal=Proceedings of the ACM SIGCHI Conference on Human Factors in Computing Systems|series=CHI '97|___location=New York, NY, USA|publisher=ACM|pages=295–302|doi=10.1145/258549.258760|isbn=0897918029}}</ref><ref>{{Cite journal|last=Accot|first=Johnny|last2=Zhai|first2=Shumin|date=1999-01-01|title=Performance Evaluation of Input Devices in Trajectory-based Tasks: An Application of the Steering Law|url=http://doi.acm.org/10.1145/302979.303133|journal=Proceedings of the SIGCHI Conference on Human Factors in Computing Systems|series=CHI '99|___location=New York, NY, USA|publisher=ACM|pages=466–472|doi=10.1145/302979.303133|isbn=0201485591}}</ref>.
==== [[Control theory|Manual Control Theory]] ====
