{{Short description|Software user interface}} {{Machine learning}} '''Human-in-the-loop''' ('''HITL''') is used in multiple contexts. It can be defined as a model requiring human interaction.<ref>"DoD Modeling and Simulation (M&S) Glossary", DoD 5000.59-M, DoD, January 1998 {{cite web |url=http://www.dtic.mil/whs/directives/corres/pdf/500059m.pdf |title=Directives Division |accessdate=2009-04-22 |url-status=dead |archiveurl=https://web.archive.org/web/20070710104756/http://www.dtic.mil/whs/directives/corres/pdf/500059m.pdf |archivedate=2007-07-10 }}</ref><ref>Karwowski, Waldemar, ''[https://books.google.com/books?id=3hkbHSV81XMC&pg=PA2407 International encyclopedia of ergonomics and human factors]'', {{ISBN|0-415-30430-X}}, 9780415304306, CRC Press, 2006</ref> HITL is associated with modeling and simulation (M&S) in the live, virtual, and constructive taxonomy. HITL, along with the related human-'''on'''-the-loop, are also used in relation to lethal autonomous weapons.<ref name=army>{{cite web|url=https://www.armyupress.army.mil/Journals/Military-Review/English-Edition-Archives/May-June-2017/Pros-and-Cons-of-Autonomous-Weapons-Systems/|title=Pros and Cons of Autonomous Weapons Systems|author1=Amitai Etzioni|author2=Oren Etzioni|work=army.mil|date=June 2017}}</ref> Further, HITL is used in the context of machine learning.<ref name=medium>{{cite news|url=https://medium.com/vsinghbisen/what-is-human-in-the-loop-machine-learning-why-how-used-in-ai-60c7b44eb2c0|title=What is Human in the Loop Machine Learning: Why & How Used in AI?|author=Vikram Singh Bisen|date=May 20, 2020|work=medium.com}}</ref>It is also used in conversational AI to manage complex interactions that require human empathy.

==Machine learning== In machine learning, HITL is used in the sense of humans aiding the computer in making the correct decisions in building a model.<ref name=medium /> HITL improves machine learning over random sampling by selecting the most critical data needed to refine the model.<ref name=schizophrenia>{{cite journal|title=Improving the Applicability of AI for Psychiatric Applications through Human-in-the-loop Methodologies|author1=Chelsea Chandler|author2=Peter W Foltz|author3=Brita Elvevåg|date=26 May 2022|journal=Schizophrenia Bulletin|volume=48|issue=5|pages=949–956|doi=10.1093/schbul/sbac038|pmid=35639561 |pmc=9434423 }}</ref>

==Simulation== In simulation, HITL models may conform to human factors requirements as in the case of a mockup. In this type of simulation, a human is always part of the simulation and consequently influences the outcome in such a way that is difficult if not impossible to reproduce exactly. HITL also readily allows for the identification of problems and requirements that may not be easily identified by other means of simulation.

HITL is often referred to as an interactive simulation, which is a special kind of physical simulation in which physical simulations include human operators, such as in a flight or a driving simulator.

===Benefits=== Human-in-the-loop allows the user to change the outcome of an event or process. The immersion effectively contributes to a positive transfer of acquired skills into the real world. This can be demonstrated by trainees utilizing flight simulators in preparation to become pilots.

HITL also allows for the acquisition of knowledge regarding how a new process may affect a particular event. Utilizing HITL allows participants to interact with realistic models and attempt to perform as they would in an actual scenario. HITL simulations bring to the surface issues that would not otherwise be apparent until after a new process has been deployed. A real-world example of HITL simulation as an evaluation tool is its usage by the Federal Aviation Administration (FAA) to allow air traffic controllers to test new automation procedures by directing the activities of simulated air traffic while monitoring the effect of the newly implemented procedures.<ref>Sollenberger, R. (2005). Human-in-the-Loop Simulation Evaluating the Collocation of the User Request Evaluation Tool. U.S. Department of Transportation Federal Aviation Administration, 1. Retrieved July 19, 2010, from http://hf.tc.faa.gov/technotes/dot-faa-ct-tn04-28.pdf {{Webarchive|url=https://web.archive.org/web/20100609162019/http://hf.tc.faa.gov/technotes/dot-faa-ct-tn04-28.pdf |date=2010-06-09 }}</ref>

As with most processes, there is always the possibility of human error, which can only be reproduced using HITL simulation. Although much can be done to automate systems, humans typically still need to take the information provided by a system to determine the next course of action based on their judgment and experience. Intelligent systems can only go so far in certain circumstances to automate a process; only humans in the simulation can accurately judge the final design. Tabletop simulation may be useful in the very early stages of project development for the purpose of collecting data to set broad parameters, but the important decisions require human-in-the-loop simulation.<ref>{{Cite web |date=2007 |title=‘Human-in-the-loop’ simulation: The right tool for port design |url=http://www.marinesafety.com/research/documents/HumanintheloopSimulationasPublishedinPortTechnologyInternationalIssue32.pdf |url-status=dead |archive-url=https://web.archive.org/web/20110714034605/http://www.marinesafety.com/research/documents/HumanintheloopSimulationasPublishedinPortTechnologyInternationalIssue32.pdf |archive-date=2011-07-14 |website=marinesafety.com |publisher=Port Technology International}}</ref> HITL reflects scenarios where human input remains essential despite advances in automation.

=== Within the virtual simulation taxonomy === Virtual simulations inject HITL in a central role by exercising motor control skills (e.g. flying an airplane), decision making skills (e.g. committing fire control resources to action), or communication skills (e.g. as members of a C4I team).

=== Examples=== *Flight simulators *Driving simulators *Marine simulators *Video games * Supply chain management simulators<ref>{{Cite journal |last=Pinto |first=Roberto |last2=Mettler |first2=Tobias |last3=Taisch |first3=Marco |date=2013-01-01 |title=Managing supplier delivery reliability risk under limited information: Foundations for a human-in-the-loop DSS |url=https://www.sciencedirect.com/science/article/pii/S0167923612002886 |journal=Decision Support Systems |volume=54 |issue=2 |pages=1076–1084 |doi=10.1016/j.dss.2012.10.033 |issn=0167-9236|url-access=subscription }}</ref> * Digital puppetry

===Misconceptions=== Although human-in-the-loop simulation can include a computer simulation in the form of a synthetic environment, computer simulation is not necessarily a form of human-in-the-loop simulation, and is often considered as human-out-of-the loop simulation. In this particular case, a computer model’s behavior is modified according to a set of initial parameters. The results of the model differ from the results stemming from a true human-in-the-loop simulation because the results can easily be replicated time and time again, by simply providing identical parameters.

==Weapons==

===Taxonomy=== {{main|Lethal autonomous weapon}} Three classifications of the degree of human control of autonomous weapon systems were laid out by Bonnie Docherty in a 2012 Human Rights Watch report.<ref name=army /> *'''human-in-the-loop''': a human must instigate the action of the weapon (in other words not fully autonomous) *'''human-on-the-loop''': a human may abort an action *'''human-out-of-the-loop''': no human action is involved

===Positive human action=== In discussions of autonomous weapons and nuclear command and control, the phrase '''positive human action''' has been used alongside "human-in-the-loop" to emphasize that a human operator must affirmatively authorize the use of force.<ref>{{cite web |last=Fink |first=Anya |title=What Is Meaningful Human Control, Anyway? Cracking the Code on Autonomous Weapons and Human Judgment |url=https://mwi.westpoint.edu/what-is-meaningful-human-control-anyway-cracking-the-code-on-autonomous-weapons-and-human-judgment/ |website=Modern War Institute at West Point |date=2024}}</ref><ref>{{cite report |title=FY25 NDAA Final Summary |publisher=Center for Arms Control and Non-Proliferation |date=2024 |url=https://armscontrolcenter.org/wp-content/uploads/2024/12/FY25-NDAA-Final-Summary.pdf |quote=Final: Adopts House provision but changes statement of policy to require "positive human actions" instead of "human in the loop".}}</ref>

Descriptions of the United States Navy's Aegis Combat System have used the phrase in characterizing a requirement for affirmative human action to initiate live firing. A survey of autonomous weapons systems described the Aegis "Auto SM" mode as one in which "the system fully develops the engagement process however engagement requires positive human action".<ref>{{cite web |title=Lethal Autonomous Weapons Systems and Artificial Intelligence: Trends, Challenges, and Policies |url=https://wise-intern.org/wp-content/uploads/2019/04/Raine_S_-FinalPaper.pdf}}</ref>

The phrase entered United States federal law in the National Defense Authorization Act for Fiscal Year 2025, which stipulates that artificial intelligence systems not compromise "the principle of requiring positive human actions in execution of decisions by the President with respect to the employment of nuclear weapons".<ref>{{cite web |title=10 USC Ch. 24: NUCLEAR POSTURE |url=https://uscode.house.gov/view.xhtml?path=/prelim@title10/subtitleA/part1/chapter24&edition=prelim |website=Office of the Law Revision Counsel of the United States House of Representatives}}</ref><ref>{{cite web |title=10 USC 491: Nuclear weapons employment strategy of the United States: reports on modification of strategy |url=https://uscode.house.gov/view.xhtml?edition=prelim&num=0&req=granuleid:USC-prelim-title10-section491 |website=Office of the Law Revision Counsel of the United States House of Representatives}}</ref>

==See also== {{Wiktionary|in the loop}} *Humanistic intelligence, which is intelligence that arises by having the human in the feedback loop of the computational process<ref>{{Cite journal |last=Minsky |first=Marvin |last2=Kurzweil |first2=Ray |last3=Mann |first3=Steve |date=2013 |title=The society of intelligent veillance |url=https://ieeexplore.ieee.org/document/6613095 |journal=Technology and Society |publisher=IEEE}}</ref> * Reinforcement learning from human feedback * MIM-104 Patriot - Examples of a human-on-the-loop lethal autonomous weapon system posing a threat to friendly forces.

==References== {{Reflist}}

Category:Ethics of science and technology Category:Machine learning Category:Military technology Category:Military terminology Category:Military robots Category:Military simulation