The SAMMIE computer-aided workplace and work task design system is intended to facilitate the consideration of human factors within the design process from the conceptual, pre-mock-up stage of design onwards. The software consists of six main parts: a computerized man-model, a workplace modelling system, a language with which to describe the work tasks to be performed in that workplace, heuristic rules for workplace layouts, various measures of effectiveness which can aid the assessment of the suitability of the workplace, and finally a system for interactive man-machine communication. The workspace model and the model of the operator are displayed on a screen of an interactive graphics terminal and the workspace is then evaluated for an operator performing specified tasks. The dimensions and arrangements of the workspace, the dimensions of the operator, and to a lesser extent the work task may all be interactively changed, and the proposed design then reevaluated. Measures of effectiveness include reach, checks on visual suitability, and an evaluation of the methods and times required to perform the task. These, and other measures, may be used by the computer itself, and interactively under the designer's control.