COGNITIVE TASK-ANALYSIS - HARMONIZING TASKS TO HUMAN CAPACITIES

This paper presents the development of a cognitive task analysis that assesses the task load of jobs and provides indicators for the redesig n of jobs. General principles of human task performance were selected and, subsequently, integrated into current task modelling techniques. The resulting cognitive task analysis centres around four aspects of t ask load: the number of actions in a period, the ratio between knowled ge- and rule-based actions, lengthy uninterrupted actions, and momenta ry overloading. The method consists of three stages: (1) construction of a hierarchical task model, (2) a time-line analysis and task load a ssessment, and (3), if necessary, adjustment of the task model. An app lication of the cognitive task analysis in railway traffic control sho wed its benefits over the 'old' task load analysis of the Netherlands Railways. It provided a provisional standard for traffic control jobs, conveyed two load risks-momentary overloading and underloading-and re sulted in proposals to satisfy the standard and to diminish the two lo ad risk.