human applied factors

Lecture 8: What are the learning objectives for Task Analysis?

1) Describe and implement Hierarchical Task Analysis (HTA) for common tasks. 2) Differentiate Job Demands Analysis (JDA) from Functional Capacity Evaluation (FAE/FCE). 3) Apply these analyses to a case.

What is task analysis?

A process that determines all steps and components required to accomplish a goal. It helps explain how a task is performed and how to optimize it for efficiency.

What four questions guide a task analysis?

1) How was the task performed? 2) What was needed to perform it? 3) Why is it performed this way? 4) How can performance be improved?

How is task analysis commonly framed in human factors?

Often as human-machine interaction: an operator has a goal to achieve using a system. Task analysis can also be a key step in a broader Job Demands Analysis.

What comparison does task analysis help make?

It supports a formal comparison between the demands a task places on a human operator and the capabilities the operator has to meet those demands.

What is the main aim of task analysis in system design?

To systematically compare work-system capabilities with work demands so designers can identify requirements and build or redesign systems that help users achieve their goals.

What can happen if task analysis is skipped before system design?

A system may be deficient because it does not adequately meet the demands of the tasks users need to perform.

What kinds of outputs can task analysis provide?

Design requirements; goal/subgoal flowcharts; information about error probability and severity; training objectives; cognitive-demand tables; automation levels; and performance-evaluation criteria.

What are the three domains of the Integrated Systems Model (ISM)?

Task, individual, and environment.

Which components are included in the ISM task domain?

Movement/task categories include mobility, stability, and manipulation; tasks can also be considered by context and by whether they are discrete or continuous.

Which components are included in the ISM individual domain?

Cognition, action, and perception. Examples include attention and planning, motor command/output, and awareness of the body in space.

How can the environment affect movement in the ISM?

Environmental factors can be regulatory or nonregulatory and may affect movement directly or indirectly.

Why must task context be considered?

The same movement or action may have different requirements depending on the goal and situation in which it is performed.

What is Hierarchical Task Analysis (HTA)?

Identification and description of a task within a system in terms of goals and subgoals, organized hierarchically and including feedback loops.

What is the highest level of an HTA?

The overall operation, defined by its goal. The goal should be expressed in real terms, such as production units, quality, or another criterion.

How are suboperations defined in HTA?

Each suboperation is defined by a subgoal and measured by its contribution to the overall system output or goal, using performance standards or criteria.

What is the relationship between an operation and its suboperations in HTA?

They have a hierarchical inclusion relationship: suboperations are components of the larger operation. They may occur in sequence, but not always.

Does HTA have to be presented as a flowchart?

No. HTA can be represented narratively or as a flowchart; the format should make the goals, subgoals, and their relationships clear.

What is a plan in HTA?

A description of how subgoals are organized or carried out to achieve the overall goal, including their sequence when relevant.

What is the difference between a hierarchical plan and feedback-based HTA?

A plan can prescribe how a task should be carried out in advance. Feedback-based HTA checks whether the intended result occurred and allows repetition or correction.

What does TOTE stand for?

Test-Operate-Test-Exit.

What is a TOTE unit?

A decision-making cycle used to determine whether a goal has been achieved through a subgoal. It relies on information feedback, a control system, and hierarchical organization.

What happens during the first Test in TOTE?

Check the current condition against the desired goal or criterion.

What happens during Operate in TOTE?

Perform an action intended to change the condition toward the goal.

What happens during the second Test in TOTE?

Check whether the operation produced the intended result.

What does Exit mean in TOTE?

Leave that particular cycle when its required condition is met. Exiting one subgoal does not necessarily mean the entire task is finished.

Why is feedback important in HTA/TOTE?

Feedback compares what actually happened with what was intended and helps determine whether to continue, repeat, or correct an action.

How does the lecture's hammering-a-nail example illustrate TOTE?

Test whether the nail is flush; hammer it if needed; test again; exit that subgoal when the nail is flush. Other subgoals may still remain before the overall task is complete.

What is Job Demands Analysis (JDA)?

A systematic quantification of the physical, cognitive, and environmental demands of a task or job.

What is a Physical Demands Analysis/Description?

An objective description of the physical demands required to complete the essential and non-essential tasks of a job.

What is a Cognitive Demands Analysis/Description?

An objective evaluation of the cognitive, emotional, and psychological skills needed to perform essential and non-essential job tasks.

What job information can a JDA include?

Job/role description, safety requirements, training, work hours, skill requirements, equipment used, and work-environment description.

What physical task details can a JDA measure?

Weight lifted, carried, or lowered; tools used; distance walked; push/pull force; task frequency; and reach distance to an object, control, or tool.

Why does a JDA identify essential and non-essential tasks?

To document what the job requires and clarify the demands associated with the different tasks in the role.

What is a Functional Abilities/Capacity Evaluation (FAE/FCE)?

A comprehensive, objective evaluation of a worker's abilities.

What does an FAE/FCE aim to identify?

Current abilities, barriers, and immediate or longer-term risks that could arise if the worker resumed regular work.

How are abilities assessed in an FAE/FCE?

Through measurable tests that quantify abilities and compare them with job demands; tasks or job skills may be simulated to identify return-to-work risks.

What physical tests might an FAE/FCE include?

Musculoskeletal examination and functional tasks such as walking, stair climbing, gripping, lifting, pushing, and pulling.

What fine-motor and cognitive abilities might an FAE/FCE assess?

Fine-motor skills, memory, attention, problem solving, judgment, and safety awareness.

What communication, sensory, and interpersonal abilities might an FAE/FCE assess?

Reading, writing, speech, interpersonal skills, hearing, vision, and perception.

JDA vs FAE/FCE: What is the key difference?

JDA evaluates what the job requires; FAE/FCE evaluates what the worker can currently do and identifies barriers or risks.

Why should JDA and FAE/FCE information be linked?

Comparing job demands with the person's capacity helps identify mismatches and decide what changes are needed to the job or support provided.

What if a worker's capacity meets or exceeds the job demands?

There is a better match between what the job requires and what the worker can do, though the relevant demands and abilities still need to be considered.

What if job demands exceed a worker's capacity?

There is a mismatch. Options include increasing effective capacity/support or reducing or modifying the job demands.

What are two broad strategies for resolving a demand-capacity mismatch?

1) Increase capacity or support, such as training or assistive devices. 2) Reduce demands by modifying work or changing job requirements.

How can assistive devices change effective capacity?

They can help a person perform a task with less physical effort or by changing how the task is completed—for example, using a dolly to move a heavy box.

How can modified work reduce job demands?

Temporarily or permanently change tasks or requirements so the worker does not have to perform duties that exceed current capacity.

What is the lecture's 12 kg box example meant to illustrate?

A mismatch between a task demand and a person's capacity can be addressed by changing the support/equipment or by changing the task itself.

What does the speed-accuracy trade-off mean?

As movement speed increases, accuracy may decrease; task performance may require balancing speed with precision.

Mr. Steacie case: What are the key facts?

He has been off work for six weeks after a back injury playing basketball, is returning to a butcher job in a large grocery store, and has been advised to avoid physically demanding tasks until eight weeks post-injury.

Mr. Steacie case: What is the purpose of the JDA?

Document the butcher job's actual demands, including tasks, weights, lifting/carrying, pushing/pulling, reaching, frequency, tools/equipment, safety, hours, and essential versus non-essential duties.

Mr. Steacie case: What is the purpose of the FAE/FCE?

Objectively assess his current abilities and barriers, using relevant physical and functional tests, to identify risks and compare capacity with butcher-job demands.

Mr. Steacie case: What should the ergonomist do with the JDA and FAE/FCE findings?

Compare the job demands with his current capacity, identify tasks that exceed restrictions, and recommend suitable accommodations for the two-week period.

Mr. Steacie case: What accommodation approaches fit the lecture's framework?

Reduce demands through modified duties and/or provide appropriate support or equipment. Avoid assigning physically demanding tasks during the physician's restriction period.

Exam application: How do you structure an answer about a worker returning after injury?

1) Describe job demands with a JDA. 2) Assess current capacity with an FAE/FCE. 3) Compare demand and capacity. 4) Identify mismatches and propose modifications/support. 5) Reassess as appropriate.

What are the three core topics to be able to explain from this lecture?

How to describe and apply HTA; how JDA differs from FAE/FCE; and how to apply both analyses to a specific case.

What are the three main topics in Lecture 9?

Occupational repetitive injuries; injuries from activities of daily life (ADL); health-related quality of life.

What are the four learning objectives for Lecture 9?

1) Employ a model for identifying how work-related musculoskeletal disorders may develop. 2) Explain how task repetition produces fatigue, error, and stress and how these interact with injury risk. 3) Give examples of repetitive injuries from ADL. 4) Define health-related quality of life and describe how repetitive injuries can reduce it.

Why does the lecture discuss repetitive injuries in the context of the task within a systems-thinking framework?

Because the way a task is designed and performed—including its forces, posture, repetition, duration, and workplace context—can contribute to injury, fatigue, error, and stress. These factors interact rather than operating in isolation.

What historical workplace changes were linked in the lecture to increases in research on repetitive injuries in the 1950s-1960s?

Automation, technology, and assembly-line work became more common, changing job requirements and the ways people performed tasks.

What workplace change in the 1980s was linked to increased research on repetitive injuries?

Widespread use of computer terminals and video display terminals (VDTs), changing how white-collar work was performed.

What change in the 1990s was discussed as a possible contributor to repetitive-injury research?

The Internet made more information available through terminals, further increasing reliance on computer-based work.

What technology trend in the 2000s and later was linked to repetitive-injury research?

Greater use of wireless and portable devices, which changed how people interact with technology and introduced different exposures and stressors.

What is the lecture's key historical point about repetitive injuries?

Changes in work technology and how tasks are performed can change the types of exposures, injuries, and stressors people experience.

What is force as a workplace injury risk factor?

The push or pull exerted on an object.

What is posture in the lecture's definition?

The ability to maintain appropriate relationships between body segments and between the body and its environment while performing a task. It includes active control of body alignment and tone relative to gravity, support surfaces, tools, the visual environment, and internal references.

What is repetition as a workplace injury risk factor?

The frequency rate at which a stress factor repeats.

What is duration as a workplace injury risk factor?

The amount of time a person is exposed to a stress factor.

How does the lecture define stress/anxiety in the workplace?

A harmful reaction to undue pressures and demands placed on a person at work. It refers to the person's response, not simply the task requirements themselves.

What are the six factors used in the lecture's Strain Index?

Intensity of exertion, duration of exertion (% of cycle), efforts per minute, hand/wrist posture, speed of work, and duration of work per day.

How is the Strain Index calculated in the lecture?

By multiplying the ratings/multipliers for intensity of exertion × duration of exertion × efforts per minute × posture × speed of work × duration per day.

What does a Strain Index rating of 1 generally represent?

The lowest-risk tier: light exertion, less than 10% of the cycle, fewer than 4 efforts per minute, very good hand/wrist posture, very slow work, and less than 1 hour per day.

What does a Strain Index rating of 5 generally represent?

The highest-risk tier: near-maximal exertion, more than 80% of the cycle, more than 20 efforts per minute, very bad hand/wrist posture, very fast work, and more than 8 hours per day.

Why does the lecture use a multiplier of Strain Index factors?

To combine several risk factors and their relative weightings into an overall indication of risk; the lecture says recognizing the combination is more important than calculating a score for this class.

In the model of work-related upper-body musculoskeletal disorders, what is exposure?

The condition of being subjected to something that has an effect on a body part. Exposure can be physical, organizational, or psychosocial.

Give examples of physical exposures in the musculoskeletal-disorder model.

Workplace layout and tool design, including a tool's size, shape, and weight.

Give examples of organizational exposures in the musculoskeletal-disorder model.

Cycle times, whether work is paced or unpaced, and the timing of rest periods.

Give examples of psychosocial exposures in the musculoskeletal-disorder model.

Job satisfaction, quality of supervision, and uncertainty about the future.

In the musculoskeletal-disorder model, what is dose?

The effect or magnitude of an exposure. Examples include tissue forces or deformations (mechanical), substrate use or metabolite production (physiological), and anxiety (psychological).

What is a primary response in the musculoskeletal-disorder model?

The actual initial change associated with the dose, often described at a physiological/cellular or tissue level—for example, changes in substrate or metabolite levels, waste accumulation, pH, muscle, temperature, tissue deformation, or pressure.

What is a secondary response in the musculoskeletal-disorder model?

The effect resulting from the primary response, such as changes in strength or mobility or the experience of psychological discomfort.

What is capacity in the musculoskeletal-disorder model?

The ability to cope with the doses to which the musculoskeletal system is exposed.

What are examples of capacity in the musculoskeletal-disorder model?

Mechanical: soft-tissue strength and bone density. Physiological: aerobic/anaerobic capacity and homeostatic control. Psychological: self-esteem and tolerance of discomfort or stress.

What is the order of the Armstrong model of work-related upper-body musculoskeletal disorders?

Exposure → Dose → Primary response → Secondary response → Capacity.

How can you remember the difference between exposure and dose?

Exposure is what the person is subjected to; dose is the effect or magnitude produced by that exposure.

How does the lecture classify repetitive/monotonous work as high, medium, or low risk?

It considers work cycle, posture and movement, freedom of action, and work content/learning. The slide uses red for higher risk, yellow for intermediate risk, and green for lower risk.

What work-cycle pattern is rated as higher risk in the lecture's repetitive/monotonous work table?

A task repeated several times per minute.

What posture and movement conditions are associated with higher risk?

Fixed, uncomfortable posture or movement with little opportunity to vary body position.

What freedom-of-action conditions are associated with higher risk?

Work completely governed by another person or system, leaving the worker little control over pace, planning, or organization.

What work-content and learning conditions are associated with higher risk?

Performing one isolated task with short training and little opportunity to learn or develop competence.

What conditions are associated with lower risk in the repetitive/monotonous work table?

A good workplace layout and opportunities to vary posture/movement; ability to fit work to one's abilities and influence planning; and work that includes several parts of the process, planning/control, and continuous skill development.

What is physical fatigue in the lecture?

A reduction in force-generating capacity or control of force output caused by repeated or sustained muscle contractions.

What are three physical-fatigue effects described in the lecture?

Reduced force-generating capacity; more variable and less precise movement; and recovery that depends partly on the timing and adequacy of rest periods.

How can physical fatigue contribute indirectly to repetitive injury?

When a person cannot maintain the same force or control, they may adopt alternative movement or gripping strategies to complete the task. Those changed strategies can create new or increased exposures that contribute to injury.

What example does the lecture use to explain alternative strategies during physical fatigue?

A worker who can no longer generate enough force to use pliers in the usual way may change how they grip or use the pliers to remove metal, potentially increasing wrist/hand strain.

Why do rest periods matter when considering physical fatigue?

Their timing and length affect recovery, and the available breaks may or may not be sufficient to overcome the physical effects of fatigue.

What is mental fatigue in the lecture?

A decline in mental task performance, including reduced vigilance and slowed responses, associated with time spent on a task.

What is vigilance?

The capacity to maintain sustained attention and detect important changes or stimuli during a task over a long period.

What happens to vigilance during a monotonous monitoring task, according to the lecture?

Detection can drop within the first 30 minutes, meaning a person may miss potentially important stimuli.

Why does the lecture use lifeguards as an example of vigilance?

Missing a critical stimulus, such as someone needing help, can have serious consequences. Rotating positions, shifts, or responsibilities may help address the limits of sustained attention.