Task Analysis at the Heart of Human-Computer Interaction

Task Analysis at the Heart of Human-Computer Interaction

Dan Diaper
DOI: 10.4018/978-1-87828-991-9.ch006
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The history of task analysis is nearly a century old, with its roots in the work of Gilbreth (1911) and Taylor (1912). Taylor’s scientific management provided the theoretical basis for production-line manufacturing. The ancient manufacturing approach using craft skill involved an individual, or a small group, undertaking, from start to finish, many different operations so as to produce a single or small number of manufactured objects. Indeed, the craftsperson often made his or her own tools with which to make end products. Of course, with the growth of civilisation came specialisation, so that the carpenter did not fell the trees or the potter actually dig the clay, but still each craft involved many different operations by each person. Scientific management’s novelty was the degree of specialisation it engendered: each person doing the same small number of things repeatedly. Taylorism thus involved some large operation, subsequently called a task, that could be broken down into smaller operations, called subtasks. Task analysis came into being as the method that, according to Anderson, Carroll, Grudin, McGrew, and Scapin (1990), “refers to schemes for hierarchical decomposition of what people do.” The definition of a task remains a “classic and under-addressed problem” (Diaper, 1989b). Tasks have been differently defined with respect to their scope: from the very large and complex, such as document production (Wilson, Barnard, & MacLean, 1986), to the very small, for example, tasks that “may involve only one or two activities which take less than a second to complete, for example, moving a cursor” (Johnson & Johnson, 1987). Rather than trying to define what is a task by size, Diaper’s (1989b) alternative is borrowed from conversation analysis (Levinson, 1983). Diaper suggests that tasks always have well-defined starts and finishes, and clearly related activities in between. The advantage of such a definition is that it allows tasks to be interrupted or to be carried out in parallel. Task analysis was always involved with the concept of work, and successful work is usually defined as achieving some goal. While initially applied to observable, physical work, as the field of ergonomics developed from World War II, the task concept was applied more widely to cover all types of work that “refocused attention on the information processing aspect of tasks and the role of the human operator as a controller, planner, diagnostician and problem solver in complex systems” (Annett & Stanton, 1998). With some notable exceptions discussed below, tasks are still generally defined with people as the agents that perform work. For example, Annett and Stanton defined task analysis as “[m]ethods of collecting, classifying and interpreting data on human performance.”

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