Presentation on theme: "Human Supervisory Control"— Presentation transcript:
116.422 Human Supervisory Control Function AllocationandTask AnalysisMassachusetts Institute of Technology
2Human Systems Engineering* “Vision”System/Software Reqs.User survey, needs analysis, etc.Feasitility assessmentArtifact and like-system evaluatioPerform ance and usatility reqsInnovative concepts forNext version releaseHE labor/budget planningInstallationPreliminary DesignSystem/SoftwareAcquisition cycleFinalize customer supportNeeds and task analysisConduct on-site assessmentStoryboards and demonstrationsProvide training materialsUl design standardsIntegration & TestDetailed DesignPlan perform ance testsDesign tradeoff and workllow analysisScenario-based assessmentDetailed Ul designs and protctypesDevelop training materialsOn-line help and documentationUnit DevelopmentHE heuristic reviewDefine perform ance and effectiveness criteriaUsatility evaluation of prototypesPlanning →Analysis→Detail Design→Test & Evaluation
4Fitts’ List Attribute Machine Human Speed Power Output Superior Comparatively slowSuperior in level in consistency Comparatively weakIdeal for consistent, repetitive actionUnreliable, learning & fatigue a factorConsistencyInformation CapacityMulti-channelPrimarily single channelIdeal for literal reproduction, access restricted and formalBetter for principles & strategies, access versatile & innovativeMemoryReasoning ComputationDeductive, tedious to program, fast & accurate, poor error correctionInductive, easier to program, slow, accurate, good error correctionGood at quantitative assessment, poor at pattern recognitionWide ranges, multi-function, judgmentSensingCopes with variation poorly, susceptible to noiseCopes with variation better, susceptible to noisePerceivingHollnagel, 2000inductiveand deductive. Induction is usually described as moving from the specific to the general, while deduction begins with the general and ends with the specific; arguments based on experience or observation are best expressed inductively, while arguments based on laws, rules, or other widely accepted principles are best expressed deductively.
5Some problems with Fitts… Tasks/functions defined in machine terms, not human-orientedIntroduces a bias“Laws of human behavior”Environmental/ecologic contextLearning, fatigue, stress, anxiety generally not incorporated into design pictureTask division vs. task complementStatic vs. dynamic allocationAdaptive allocation/automationFunction allocation is not binary•Bandwidth•Trust•Machine/computer metaphors
6Designing automation to support information processing HumanPerception/Working MemorySensory ProcessingDecisionMakingResponseSelectionAutomationDecision& Action SelectionInformation AcquisitionInformation AnalysisAction Implementation*Parasuraman, Sheridan, Wickens, 2000
7A Model of Types and Levels of Automation* What should be automated?Identify types of automationDecision& Action SelectionInformation AcquisitionInformation AnalysisAction ImplementationA Model of Types and Levels of Automation*Identify levels of automationLow (manual) High (full automation)Apply primary evaluative criteria:Human Performance Consequences•Mental workload•Situation awareness•Complacency•Skill degradationInitial types & levels of automationApply secondary evaluative criteria:•Automation reliability•Costs of action outcomesFinal types & levels of automation*Parasuraman, Sheridan, Wickens, 2000
8Sheridan and Verplank’s10 Levels of Automation of Decision and Action Selection Automation LevelAutomation DescriptionThe computer offers no assistance: human must take all decision and actions.The computer offers a complete set of decision/action alternatives, ornarrows the selection down to a few, orsuggests one alternative, andexecutes that suggestion if the human approves, orallows the human a restricted time to veto before automatic execution, orexecutes automatically, then necessarily informs humans, andinforms the human only if asked, orinforms the human only if it, the computer, decides to.The computer decides everything and acts autonomously, ignoring the human.
9A Model of Types and Levels of Automation* What should be automated?Identify types of automationDecision& Action SelectionInformation AcquisitionInformation AnalysisAction ImplementationA Model of Types and Levels of Automation*Identify levels of automationLow (manual) High (full automation)Apply primary evaluative criteria:Human Performance Consequences•Mental workload•Situation awareness•Complacency•Skill degradationInitial types & levels of automationApply secondary evaluative criteria:•Automation reliability•Costs of action outcomesFinal types & levels of automation*Parasuraman, Sheridan, Wickens, 2000
10Function Allocation Criteria No difference in the relative capabilities of human & machine.Human performance > machine performance.Machine performance > human.Machine performance is so poor that the functions should be allocated to humans.Human performance is so poor that the functions should be allocated to machine.Unacceptable performance by both human and machine.Three function allocation criteria:Balance of valueUtilitarian & cost-based allocationAllocation for affective or cognitive support.ExcellentMachineUnsatisfactoryUnsatisfactoryHumanExcellentPrice, 1985
12Task AnalysisDetermining what an operator must accomplish to meet a mission goalInteractions both on a local and system level are criticalWill contain actions and/or cognitive processesFlow process charts, operational sequence diagrams, critical task analysisAttempt to understand how a particular task could exceed human limitations, both physical and cognitiveCognitive task analysisNot the only system analytic method but a critical oneShift away from system control to systems management.Supervisory control becoming more about cognitive tasking than manual tasking, especially with increasing automation
13Cognitive Task Analysis (CTA) Goal: To analyze and represent the knowledge and cognitive activities needed in complex work domainsCTA is generally a descriptive modeling technique of workers’ knowledge and cognitionAs opposed to Computational Cognitive Models (CCM)Knowledge Elicitation techniques provide input to CTA and CCMExperts vs. NovicesEvolutionary systems vs. revolutionary systemsBackground ResearchStandards, procedures, manuals, organizational chartsField StudiesIn both real environments and high fidelity simulationsQuestionnaires/Surveys
14CTA, Cont. Interviews Observations Design Reviews Problems with CTA Individuals vs. focus groupsCritical Incident Technique/Critical Decision MethodObservationsPARI Method (Precursor (reason for action), Action, Result, Interpretation (of result))Verbal protocolsDesign ReviewsUsability, Expert, HeuristicProblems with CTALabor intensiveGenerate much data that is difficult to analyzeGap between CTA and designOpportunistic
15CTA: A Bootstrapping Process COGNITIVE TASK ANALYSISUnderstanding the way people operatein their worldDiscovering support for how peoplewill operate in their worldGoal :Understand/model expertise se, knowledge,strategies, s, and errorTechniques :Semantic MappingEthnographic / Observational investigationsCritical Incident TechniqueCritical Decision MethodStructured Interview T w TechniquesPractitioner(s)CTAModelDesigBa BasisScratchGrowth of UnderstandingField of Pr PracticeCTA RepresentationPrototype RepresentationGoal :Understand/model complexities,demands, variability, and complicatingfactorsTech chniques :Functional/Means-ends AnalysisEthnographic / Observational investigationsFunctional Task and Workflow ModelingStructured Interview TechniquesThe DomainDiscovering how to support the way the worldwill workUnderstanding the way the world worksTimeTimeExploring the Current WorldExploring the Envisioned WorldAdapted from Carnegie Group, Inc.critical decision method in which participants are asked to describe a specific decision-making incident in detail and then to respond to probes seeking elaboration of important aspects of the decision sequences.Semantic mapping (a.k.a., mind-mapping, idea mapping, word webbing, etc.) is a term which describes a variety of strategies designed to show how key words or concepts are related to one another through graphic representations.Mapping is an effectivetechnique for teaching vocabulary and textual patterns of organization; and it is also effectivefor improving note taking and creative thinking skills.
17CTA: A Bootstrapping Process COGNITIVE TASK ANALYSISUnderstanding the way people operatein their worldDiscovering support for how peoplewill operate in their worldGoal :Discovery of unsupportedexpertise, knowledge,and strategiesTechniques :Storyboard walkthroughsParticipatory designWizard-of-Oz techniqueHigh-fidelity simulationsGoal :Understand/model expertise, knowledge,strategies, s, and errorTechniques :Semantic MappingEthnographic / Observational investigationsCritical Incident TechniqueCritical Decision MethodStructured Interview T w TechniquesPractitioner(s)Growth th of UnderstandingArtifacts asHypothesesField of Pr PracticeScratchDesign BasisCTA RepresentationPrototype RepresentationThe DomainGoal :Understand/modelcomplexities,demands, variability,and complicatingfactorsTechniques :Functional/Means-ends AnalysisEthnographic / ObservationalinvestigationsFunctional Task and WorkflowModelingStructured Interview TechniquesGoal :Discovery of unsupportedcomplexities,demands, variability, andcomplicating factorsTechniques :Scenario generation based on:- Textbook cases- Complicating factors- Cascading effects- ExceptionsUnderstanding the way the world worksDiscovering how to support the way the worldwill workTimeTimeExploring the Current WorldExploring the Envisioned WorldAdapted from Carnegie Group, Inc.WoZ:
18Work Analysis v. Task Analysis Descriptive v. Normative v. PrescriptiveEcological focusConstraints v. instructionsMap v. directionsNot a mutually exclusive setnormative analysis focuses on "how decision makers should ideally perform" an activity. Bell et al. (1988) have claimed that "normative theory has something to do with how idealized, rational, super-intelligent people should think and should act." Normative analysis is often contrasted with prescriptive analysis, which is usually said to be geared toward examining what realpeople ought to do given their real-world constraints and cognitive limitations (or how decision aids might aid real decision makers).
19Resources A Survey of Cognitive Engineering Methods and Uses ONR/Aptima Cognitive Task Analysis website