Task analysis

Last updated

Task analysis is a fundamental tool of human factors engineering. It entails analyzing how a task is accomplished, including a detailed description of both manual and mental activities, task and element durations, task frequency, task allocation, task complexity, environmental conditions, necessary clothing and equipment, and any other unique factors involved in or required for one or more people to perform a given task. [1]

Contents

Information from a task analysis can then be used for many purposes, such as personnel selection and training, tool or equipment design, [2] procedure design (e.g., design of checklists, or decision support systems) and automation. Though distinct, task analysis is related to user analysis.

Safety Critical Task Analysis

Safety Critical Task Analysis (SCTA) focuses on how tasks that are critical to major accident risk are performed. SCTA is a crucial assessment designed to predict and understand the role that human error plays in major accidents. [3] This is a type or workshop conducted to support Major Accident Hazard (MAH) industries, such as oil and gas, chemicals. Those activities or tasks that are identified as being safety critical (i.e. may result in significant impact to the environment or harm to people if completed incorrectly), are put through an SCTA which would break down the task into a step-by-step process and review where the most likely points of error are to occur. The aim of this is to identify where additional control measures can be introduced that would reduce the likelihood of human error in completing such an important task.

The Energy Institute in the UK, has released a guidance document titled "Guidance on Human Factors Safety Critical Analysis" [4]

Applications

The term "task" is often used interchangeably with activity or process. Task analysis often results in a hierarchical representation of what steps it takes to perform a task for which there is a goal and for which there is some lowest-level "action" or interaction among humans and/or machines: this is known as hierarchical task analysis. Tasks may be identified and defined at multiple levels of abstraction as required to support the purpose of the analysis. A critical task analysis, for example, is an analysis of human performance requirements which, if not accomplished in accordance with system requirements, will likely have adverse effects on cost, system reliability, efficiency, effectiveness, or safety. [5] Task analysis is often performed by human factors and ergonomics professionals.

Task analysis may be of manual tasks, such as bricklaying, and be analyzed as time and motion studies using concepts from industrial engineering. Cognitive task analysis is applied to modern work environments such as supervisory control where little physical work occurs, but the tasks are more related to situation assessment, decision making, and response planning and execution. [6]

Task analysis is also used in education. It is a model that is applied to classroom tasks to discover which curriculum components are well matched to the capabilities of students with learning disabilities and which task modification might be necessary. It discovers which tasks a person hasn't mastered, and the information processing demands of tasks that are easy or problematic. In behavior modification, it is a breakdown of a complex behavioral sequence into steps. This often serves as the basis for chaining.

The results of task analysis are often represented in task models, which clearly indicate the relations among the various tasks, An example notation used to specify task models is ConcurTaskTrees (by Fabio Paternò), which is also supported by tools that are freely available. [7]

For Inclusion

Knowing how to do Task Analysis is a fundamental skill in inclusive teaching. In fact, it consists of a backward composition of the objective which leads to the construction of a map (Plan), that is, a sequence of simpler actions and abilities to achieve a specific objective.

For the Task Analysis it is necessary to clearly identify which are the prerequisites for the activity: essential prerequisites (knowledge, skills and competences of the student) and support prerequisites (environmental facilitators). It therefore requires to organize teaching and also an indispensable flexibility.

There are also three approaches: technical (students are passive tools), socio-relational (students are motivated to participate), sociotechnical (an intermediate way in which students are able to make decisions and solve problems).

The advantages

Versus work domain analysis

If task analysis is likened to a set of instructions on how to navigate from Point A to Point B, then Work domain analysis (WDA) is like having a map of the terrain that includes Point A and Point B. WDA is broader and focuses on the environmental constraints and opportunities for behavior, as in Gibsonian ecological psychology and ecological interface design (Vicente, 1999; Bennett & Flach, 2011, p. 61)

Documentation

Since the 1980s, a major change in technical documentation has been to emphasize the tasks performed with a system rather than documenting the system itself. [8] In software documentation particularly, long printed technical manuals that exhaustively describe every function of the software are being replaced by online help organized into tasks. This is part of the new emphasis on usability and user-centered design rather than system/software/product design. [9]

This task orientation in technical documentation began with publishing guidelines issued by IBM in the late 1980s. Later IBM studies led to John Carroll's theory of minimalism in the 1990s. [10]

With the development of XML as a markup language suitable for both print and online documentation (replacing SGML with its focus on print), IBM developed the Darwin Information Typing Architecture XML standard in 2000. Now an OASIS standard, DITA has a strong emphasis on task analysis. Its three basic information types are Task, Concept, and Reference. Tasks are analyzed into steps, with a main goal of identifying steps that are reusable in multiple tasks.

Hierarchical task analysis

Hierarchical task analysis (HTA) is a task description method and a variant of task analysis. Task description is a necessary precursor for other analysis techniques, including critical path analysis (CPA). HTA is used to produce an exhaustive description of tasks in a hierarchical structure of goals, sub-goals, operations and plans. [11] In HTA, tasks are broken down into progressively smaller units. [12]

Operations and plans

Operations are the actions performed by people interacting with a system or by the system itself, [13] and plans explain the conditions necessary for these operations. [1] Operations describe the smallest individual task steps in the HTA, i.e. those which cannot be broken down into plans and further operations. They are the individual actions, such as 'visually locate control' or 'move hand to control', which the user must perform in a particular combination to achieve the goal of task completion.

Applying

The following steps should be followed when conducting a HTA:

  1. Define the task under investigation and identify the purpose of the task analysis. The analyst should have some further evaluation methods in mind for which the HTA will be useful and should have reason for needing this type of analysis to be performed.
  2. Data collection – In order to carry out the HTA it is necessary to obtain data on how the task is performed. This could be collected via observation of the task in question or from a detailed specification of the device under analysis. Alternatively, interviews or questionnaires with people that have first-hand experience of performing that task could be conducted to gather the necessary detail.
  3. Define the overall task goal, which will be presented as the top level in the HTA. An example might be "increase fan speed by two steps". This describes what is being achieved by performing the task; however, at this stage there is no indication of how the task will be performed.
  4. Determine the next level of sub-goals by breaking down the overall goal. A sub-goal for the above example might be "open the climate menu". This provides more information about how to accomplish the task; however, it can still be broken down into smaller units, which will describe the individual operations (performed via the visual, manual or cognitive modes) that need to be performed.
  5. Continue breaking down the sub-goals until all operations are identified. Operations in the "reduce fan speed task" will include "move finger to climate menu button" and "touch climate menu button".
  6. Define plans to describe how to perform the operations in each sub-goal level of the hierarchy. In the fan speed example, the two operations will have to be performed in series, one after the other. The plan will instruct the user to "perform 1, then 2". Operations can also be performed in parallel, and in this case the plan would instruct the user to "perform 1 and 2 together". Numbers should be assigned to the different levels in the hierarchy.

Organising the hierarchy

Each level in the HTA should be numbered according to its hierarchical level: The overall goal is the highest hierarchical level and should be numbered 0. The first sub-goal in the hierarchy will be 1, also with plan 1. Further levels just extend this system - third hierarchical level: 1.1, fourth hierarchical level: 1.1.1, and so on. A HTA can be represented in list or diagram form. In list form lines should be indented to denote the different hierarchical levels. In diagram form each operation should be placed within a box and links should be made between them: a lower hierarchical level should branch from underneath a higher level operation. Plans should be written next to the branches to describe the way in which the branched operations should be carried out. Hence, the plans should be goal oriented to achieve the success of any field.

Applications and limitations

HTA is a task description method which is most commonly used as a starting point for further analyses such as multimodal CPA and SHERPA. [13] On its own, HTA does not provide results for usability evaluation; however, you should be able to study the HTA in order to learn about the structure of different tasks. It may also allow you to highlight unnecessary task steps or potential errors that might occur in task performance. HTA is a fairly time-consuming method to carry out as each individual operation in a task needs to be analysed; however, creating a comprehensive HTA can considerably reduce the time required for other modelling methods.

See also

Notes

  1. 1 2 Kirwan, B. and Ainsworth, L. (Eds.) (1992). A guide to task analysis. Taylor and Francis.{{cite book}}: CS1 maint: multiple names: authors list (link)
  2. ↑ Hackos, JoAnn T. & Redish, Janice C. (1998). User and Task Analysis for Interface Design. Wiley.
  3. ↑ Technical, Salus (27 October 2022). "First of its kind task analysis software sets out to reduce human error across high hazard industries". Task Analysis - New Software .
  4. ↑ Institute, Energy. "Guidance on Human Factors Safety Critical Analysis Software" (PDF). EI SCTA .
  5. ↑ DOD Data Item Description (DID) DI-HFAC-81399B: Critical Task Analysis Report. 2013.
  6. ↑ Crandall, B., Klein, G., and Hoffman, R. (2006). Working minds: A practitioner's guide to cognitive task analysis. MIT Press.{{cite book}}: CS1 maint: multiple names: authors list (link)
  7. ↑ Fabio Paternò (2002). CTTE: Support for Developing and Analysing Task Models for Interactive System Design. IEEE.
  8. ↑ Hackos and Redish, 1998
  9. ↑ Brockmann, R. John (1986). Writing Better Computer User Documentation – From Paper to Online . Wiley-Interscience. ISBN   978-0-471-88472-9.
  10. ↑ Carroll, John M. (1990). The Nurnberg Funnel – Designing Minimalist Instruction for Practical Computer Skill. MIT.
  11. ↑ Stanton, N.A.; Salmon, P.M.; Walker, G.H.; Baber, C.; Jenkins, D.P. (2005). Human factors methods: a practical guide for engineering and design. Aldershot, UK: Ashgate.
  12. ↑ Lyons, M (2010). "Towards a framework to select techniques for error prediction: supporting novice users in the healthcare sector". Applied Ergonomics. 40 (3): 379–395. doi:10.1016/j.apergo.2008.11.004. PMID   19091307.
  13. 1 2 Stanton, N.A. (2006). "Hierarchical task analysis: developments, applications, and extensions". Applied Ergonomics. 37 (1): 55–79. CiteSeerX   10.1.1.568.7814 . doi:10.1016/j.apergo.2005.06.003. PMID   16139236.

Vicente, K. J. (1999). Cognitive work analysis: Toward safe, productive, and healthy computer-based work. LEA.

Bennett, K. B., & Flach, J. M. (2011). Display and interface design: Subtle science, exact art. CRC Press.

Related Research Articles

Usability engineering is a professional discipline that focuses on improving the usability of interactive systems. It draws on theories from computer science and psychology to define problems that occur during the use of such a system. Usability Engineering involves the testing of designs at various stages of the development process, with users or with usability experts. The history of usability engineering in this context dates back to the 1980s. In 1988, authors John Whiteside and John Bennett—of Digital Equipment Corporation and IBM, respectively—published material on the subject, isolating the early setting of goals, iterative evaluation, and prototyping as key activities. The usability expert Jakob Nielsen is a leader in the field of usability engineering. In his 1993 book Usability Engineering, Nielsen describes methods to use throughout a product development process—so designers can ensure they take into account the most important barriers to learnability, efficiency, memorability, error-free use, and subjective satisfaction before implementing the product. Nielsen’s work describes how to perform usability tests and how to use usability heuristics in the usability engineering lifecycle. Ensuring good usability via this process prevents problems in product adoption after release. Rather than focusing on finding solutions for usability problems—which is the focus of a UX or interaction designer—a usability engineer mainly concentrates on the research phase. In this sense, it is not strictly a design role, and many usability engineers have a background in computer science because of this. Despite this point, its connection to the design trade is absolutely crucial, not least as it delivers the framework by which designers can work so as to be sure that their products will connect properly with their target usership.

<span class="mw-page-title-main">Usability</span> Capacity of a system for its users to perform tasks

Usability can be described as the capacity of a system to provide a condition for its users to perform the tasks safely, effectively, and efficiently while enjoying the experience. In software engineering, usability is the degree to which a software can be used by specified consumers to achieve quantified objectives with effectiveness, efficiency, and satisfaction in a quantified context of use.

A heuristic evaluation is a usability inspection method for computer software that helps to identify usability problems in the user interface design. It specifically involves evaluators examining the interface and judging its compliance with recognized usability principles. These evaluation methods are now widely taught and practiced in the new media sector, where user interfaces are often designed in a short space of time on a budget that may restrict the amount of money available to provide for other types of interface testing.

User-centered design (UCD) or user-driven development (UDD) is a framework of processes in which usability goals, user characteristics, environment, tasks and workflow of a product, service or process are given extensive attention at each stage of the design process. These tests are conducted with or without actual users during each stage of the process from requirements, pre-production models and post production, completing a circle of proof back to and ensuring that "development proceeds with the user as the center of focus." Such testing is necessary as it is often very difficult for the designers of a product to understand intuitively the experiences of first-time users, and what each user's learning curve may look like. User-centered design is based on the understanding of a user, their demands, priorities and experiences and when used, is known to lead to an increased product usefulness and usability as it delivers satisfaction to the user. User-centered design applies cognitive science principles to create intuitive, efficient products by understanding users' mental processes, behaviors, and needs.

<span class="mw-page-title-main">Requirements analysis</span> Engineering process

In systems engineering and software engineering, requirements analysis focuses on the tasks that determine the needs or conditions to meet the new or altered product or project, taking account of the possibly conflicting requirements of the various stakeholders, analyzing, documenting, validating, and managing software or system requirements.

<span class="mw-page-title-main">Systems development life cycle</span> Systems engineering terms

In systems engineering, information systems and software engineering, the systems development life cycle (SDLC), also referred to as the application development life cycle, is a process for planning, creating, testing, and deploying an information system. The SDLC concept applies to a range of hardware and software configurations, as a system can be composed of hardware only, software only, or a combination of both. There are usually six stages in this cycle: requirement analysis, design, development and testing, implementation, documentation, and evaluation.

The following outline is provided as an overview of and topical guide to human–computer interaction:

<span class="mw-page-title-main">Checklist</span> Aide-memoire to ensure consistency and completeness in carrying out a task

A checklist is a type of job aid used in repetitive tasks to reduce failure by compensating for potential limits of human memory and attention. Checklists are used both to ensure that safety-critical system preparations are carried out completely and in the correct order, and in less critical applications to ensure that no step is left out of a procedure. they help to ensure consistency and completeness in carrying out a task. A basic example is the "to do list". A more advanced checklist would be a schedule, which lays out tasks to be done according to time of day or other factors, or a pre-flight checklist for an airliner, which should ensure a safe take-off.

The cognitive walkthrough method is a usability inspection method used to identify usability issues in interactive systems, focusing on how easy it is for new users to accomplish tasks with the system. A cognitive walkthrough is task-specific, whereas heuristic evaluation takes a holistic view to catch problems not caught by this and other usability inspection methods. The method is rooted in the notion that users typically prefer to learn a system by using it to accomplish tasks, rather than, for example, studying a manual. The method is prized for its ability to generate results quickly with low cost, especially when compared to usability testing, as well as the ability to apply the method early in the design phases before coding even begins.

GOMS is a specialized human information processor model for human-computer interaction observation that describes a user's cognitive structure on four components. In the book The Psychology of Human Computer Interaction. written in 1983 by Stuart K. Card, Thomas P. Moran and Allen Newell, the authors introduce: "a set of Goals, a set of Operators, a set of Methods for achieving the goals, and a set of Selections rules for choosing among competing methods for goals." GOMS is a widely used method by usability specialists for computer system designers because it produces quantitative and qualitative predictions of how people will use a proposed system.

Situational awareness or situation awareness (SA) is the understanding of an environment, its elements, and how it changes with respect to time or other factors. Situational awareness is important for effective decision making in many environments. It is formally defined as:

“the perception of the elements in the environment within a volume of time and space, the comprehension of their meaning, and the projection of their status in the near future”.

Ecological interface design (EID) is an approach to interface design that was introduced specifically for complex sociotechnical, real-time, and dynamic systems. It has been applied in a variety of domains including process control, aviation, and medicine.

Cognitive ergonomics is a scientific discipline that studies, evaluates, and designs tasks, jobs, products, environments and systems and how they interact with humans and their cognitive abilities. It is defined by the International Ergonomics Association as "concerned with mental processes, such as perception, memory, reasoning, and motor response, as they affect interactions among humans and other elements of a system. Cognitive ergonomics is responsible for how work is done in the mind, meaning, the quality of work is dependent on the persons understanding of situations. Situations could include the goals, means, and constraints of work. The relevant topics include mental workload, decision-making, skilled performance, human-computer interaction, human reliability, work stress and training as these may relate to human-system design." Cognitive ergonomics studies cognition in work and operational settings, in order to optimize human well-being and system performance. It is a subset of the larger field of human factors and ergonomics.

The system safety concept calls for a risk management strategy based on identification, analysis of hazards and application of remedial controls using a systems-based approach. This is different from traditional safety strategies which rely on control of conditions and causes of an accident based either on the epidemiological analysis or as a result of investigation of individual past accidents. The concept of system safety is useful in demonstrating adequacy of technologies when difficulties are faced with probabilistic risk analysis. The underlying principle is one of synergy: a whole is more than sum of its parts. Systems-based approach to safety requires the application of scientific, technical and managerial skills to hazard identification, hazard analysis, and elimination, control, or management of hazards throughout the life-cycle of a system, program, project or an activity or a product. "Hazop" is one of several techniques available for identification of hazards.

The Technique for human error-rate prediction (THERP) is a technique that is used in the field of Human Reliability Assessment (HRA) to evaluate the probability of human error occurring throughout the completion of a task. From such an analysis, some corrective measures could be taken to reduce the likelihood of errors occurring within a system. The overall goal of THERP is to apply and document probabilistic methodological analyses to increase safety during a given process. THERP is used in fields such as error identification, error quantification and error reduction.

<span class="mw-page-title-main">Human–computer interaction</span> Academic discipline studying the relationship between computer systems and their users

Human–computer interaction (HCI) is research in the design and the use of computer technology, which focuses on the interfaces between people (users) and computers. HCI researchers observe the ways humans interact with computers and design technologies that allow humans to interact with computers in novel ways. A device that allows interaction between human being and a computer is known as a "Human-computer Interface (HCI)".

Tools, devices or software must be evaluated before their release on the market from different points of view such as their technical properties or their usability. Usability evaluation allows assessing whether the product under evaluation is efficient enough, effective enough and sufficiently satisfactory for the users. For this assessment to be objective, there is a need for measurable goals that the system must achieve. That kind of goal is called a usability goal. They are objective criteria against which the results of the usability evaluation are compared to assess the usability of the product under evaluation.

<span class="mw-page-title-main">Ergonomics</span> Designing systems to suit their users

Ergonomics, also known as human factors or human factors engineering (HFE), is the application of psychological and physiological principles to the engineering and design of products, processes, and systems. Primary goals of human factors engineering are to reduce human error, increase productivity and system availability, and enhance safety, health and comfort with a specific focus on the interaction between the human and equipment.

Cognitive work analysis (CWA) is a framework that was developed to model a complex sociotechnical system.

Human performance modeling (HPM) is a method of quantifying human behavior, cognition, and processes. It is a tool used by human factors researchers and practitioners for both the analysis of human function and for the development of systems designed for optimal user experience and interaction. It is a complementary approach to other usability testing methods for evaluating the impact of interface features on operator performance.

This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.