AN INVESTIGATION OF HUMAN PERFORMANCE IN A TWO-STAGE COMBINED MANUAL AND DECISION TASK UNDER DIFFERENT WORK-LOAD CONDITIONS.

Many industrial control tasks can be described as Combined Manual and Decision Tasks (CMDT). The objective of this study was to investigate and optimize the performance time of operators in a two-stage CMDT. An experimental situation for this study was derived from a real industrial task. The apparatus used was a two-stage CMDT, or put more precisely, a simulation of a semi-automatic punch press machine commonly used in the steel fabrication industry. The experiment consisted of four major conditions, comprised of one of two activations, i.e., either unimanual or bimanual paired with each of the two stimulative repetitions, i.e., either random or sequential. Under each of the four experimental conditions, a central composite design was applied. The design included three levels of information load, three levels of machine time lag, and three levels of probability distribution of emergency signal occurrences. Twenty male subjects participated in the experiments. In addition to the performance time measure, the dual task approach, using the simple task of foot tapping as the secondary task, was applied to obtain the quantitative measurement of Perceptual Motor Load (PML) for a CMDT. PML Score using Michon\u27s scoring method, PML Index developed in this study, and Heart Rate Variability (HRV) as a physiological measure of PML were measured during the experiments to determine if the task requirements were well matched with a worker\u27s mental capability. Utilizing response surface method, prediction models of human performance in a two-stage CMDT were developed and optimal conditions found. An additional interest of this study was to develop a new scoring method for PML, since Michon\u27s scoring method did not sufficiently take into account statistical characteristics of PML as effected by the primary task. The results of PML study showed that the new scoring method contributed a better measure of PML in the task.Dept. of Industrial and Manufacturing Systems Engineering. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis1988 .O438. Source: Dissertation Abstracts International, Volume: 48-10, Section: B, page: 3074. Thesis (Ph.D.)--University of Windsor (Canada), 1988