A study of perceptual motor load as affected by combined manual and decision task characteristics.

This paper presents an experimental study of Perceptual Motor Load (PML) in a Combined Manual and Decision Task (CMDT). The purpose of this study was to compare Michon's scoring method of measuring PML with a new scoring method as affected by a two-stage CMDT under different work-load conditions. The dual task approach, using the simple task of foot tapping as the secondary task, was applied to obtain the quantitative measurement of PML. 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 time lag, and three levels of probability distribution of emergency signal occurrences. Twenty male subjects participated in the experiments. No significant difference between the results of both scoring methods was found; however, the new scoring method can contribute a better measure of PML in terms of correlation coefficients between the scores and the performance times.