Task Analysis

Task analysis is an essential tool for researchers in human factors. It is often done very early in the design process, but can also be useful later in the design cycle during the testing and evaluation phase. Many of the more complex methods available for researchers in the field rely on an analysis of the task as the first step in the process. Therefore, task analysis methods are arguably the most important for any human factors/user-experience researcher to master.

Any given task can be thought of in terms of its end goal, which can typically be broken down into sub-goals/sub-tasks that are arranged hierarchically. Take for example the task of making a grilled cheese sandwich for lunch. The primary goal is to prepare a delicious grilled cheese sandwich to curb your hunger, but in order to accomplish this you need to complete several sub-tasks. These would include things like heating up a pan, spreading butter on the bread, placing cheese slices on the non-buttered side of the bread, etc. While this is a simplistic example, breaking the larger task down makes it clear that preparing a grilled cheese sandwich involves multiple steps and requires perceptual, motor, and cognitive abilities. For example, monitoring the color of the bread to prevent burning (perceptual), spreading butter without puncturing bread with your knife (motor), and memory of ingredients and procedure (cognitive). By doing even a cursory break down of this task we now have a better description of the grilled-cheese making process and what the task requires of the grilled-cheese maker. This is the basic idea behind task analysis.

Task analysis can be helpful when you are interested in defining a user's objectives within a complex task, describing the user's subtasks in detail, specifying the types of knowledge needed to complete a given task, developing training, or evaluating performance.

A complete task analysis consists of the following steps:

Data collection - Observe someone performing a structured task (e.g., present a scenario or instruct them to use a particular product/system). In cases where observation is not possible, interviewing a task expert may be appropriate.
Construct a task lexicon and taxonomy - Make a list of precisely defined terms that you will use to describe the task, which may include both functions (e.g., click, scroll) and specific behaviors (e.g., search, pause, navigate). This ensures that others viewing the description will have the same understanding of the terms used that you do. A taxonomy categorizes or groups terms that are similar semantically, in complexity, or that occur in similar parts of the task. A taxonomy can be especially useful if you have a large lexicon. Both of these components are helpful if other analysts need to replicate your task analysis or if you need to reanalyze the task at a later time.
Create a task description - Decomposition of a task that consists of a temporal sequence of steps. This can be represented in a narrative, tabular, or flow chart format. This decomposition should guide the reader step-by-step through the process of the task being analyzed.
Analyze results - There are a variety of analytical methods for elaborating on the descriptive information about the task that was developed in the previous step (see below for a list of options). The choice of method will depend on the goal of the analysis, the time and resources available, and the desired level of detail for the analysis.

One of the benefits of task analysis is that it is a very flexible tool that can be designed to meet your specific needs. For example, a task description may be enough information for your purposes, and you may opt to skip formal analytical methods. Alternatively, a taxonomy of terms may be unnecessary if you only have a few items in your lexicon or if you are under a time-crunch. The key is to tailor the method to your project objectives and constraints.

Task analysis methods are designed to break down complex tasks into a sequence of steps to achieve a better understanding of the process. Below is a list of some methods to analyze findings from a task analysis. This list represents a summary of commonly-used methods, but is by no means exhaustive. For more specific details on each type of analysis, we encourage you to read the articles provided in the references section below.

Hierarchical task analysis
Goals, operators, methods, and selection rules (GOMS) modeling

Four popular variants:

- - - Keystroke-Level Model (KLM-GOMS)
    - Card , Moran, and Newell (CMN-GOMS)
    - Natural GOMS Language (NGOMSL)
    - Critical-Path Method (CPM-GOMS)
Modular task analysis
PRONET
Multidimensional scaling

References:

Arthur, W., Glaze, R. M., Bhupatkar, A., Villado, A. J., Bennett, W., & Rowe, L. J. (2012). Team Task Analysis: Differentiating Between Tasks Using Team Relatedness and Team Workflow as Metrics of Team Task Interdependence. Human Factors, 54(2), 277–295. https://doi.org/10.1177/0018720811435234
Gillan, D. J. (2012). Five questions concerning task analysis. In M. A. Wilson, W. R. Bennett, S. G. Gibson, G. M. Alliger (Eds.), The handbook of work analysis: Methods, systems, applications and science of work measurement in organizations (pp. 201-213). Routledge.
John, B. E., and Kieras, D.E. (1996). The GOMS family of user interface analysis techniques: comparison and contrast. ACM Trans. Comput.-Hum. Interact, 3(4), 320–351. https://doi.org/10.1145/235833.236054
Bohil, C. J., Higgins, N. A., & Keebler, J. R. (2014). Predicting and interpreting identification errors in military vehicle training using multidimensional scaling. Ergonomics, 57(6), 844-855. https://doi.org/10.1080/00140139.2014.899631

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