Analysis Techniques For Man-Machine Systems Design

NATO UNCLASSIFIED- 63 - AC/243(Panel-8')TR/7Volume 2Ls. 4 TASK ANALYSIS- mission &scenarioanalysis4 O. C altsk analysisi f- function workspaceallocation task designt tanalysiso4.4 funcomtion/at~ rAto/nomto auain- Verformnance4.1 * Timelines4.2 *-Flow process chartsEssentially, a task is a system function th~at has been allocated to a human operator. Meister (1971) defines task as anoperator activity that includes an immediate purpose, a machine output or consequences of action, and the humaninputs, decisions, and outputs needed to accomplish the purpose. Task analysis is one of the most common activitiesof the human engineering specialist. There are two major goals of task analysis: one is to define what an operatorwill be required to do 2 , to permit the application of relevant knowledge on human performance; the other goal is todefine what an operator will do in order to determine how he or she will interact with the rest of the system. Acompleted task analysis specifies the activities of the operator, in the same way that other analyses specify what it isthat the system hardware and software do (see DeGreene, 1970; Drury et al., 1987; Gillies, 1984; Laughery &Laughery, 1987; and Woodson, 1981).BackgroundTask analysis is central to the design of the system and the human-machine interface and has been a key tool in2 The terms task synthesis or task description are sometimes used for the analysis of what an operator willbe required to do in systems under development, and the term task analysis is sometimes reserved for analyses oftasks in existing systems. There is no standardization in the use of such terms, however, and "task analysis" isused here for simplicity.NATO UNCLASSIFIED-eS3