Psychophysiological assessment of an adaptive asynchronous human-machine system with the dual-task method.

Human error is one of the leading causes of industrial accidents at modern manufacturing production sites. An adaptive asynchronous human-machine system (Async-HMS) was previously proposed as a new mechanism for preventing the reduction of cognitive level by controlling the actual operation period of machines that lead to monotonous behavior. The objective of this paper is to assess Async-HMS from the aspects of person's current capacity for performing processing resources. A dual-task method consisting of a synchronization task with three periodic fluctuations and four levels of difficulties of mental arithmetic tasks was conducted with Async-HMS on a PC. The three periodic fluctuations are constant periodic fluctuation (Cnst), perceptible periodic fluctuation (Supraliminal), and imperceptible periodic fluctuation (Subliminal). The task performance and the psychophysiological state were assessed through the dual-task method. In an ANOVA analysis, the time shared fraction, which is an index of processing resources devoted to an arithmetic task, had no significant effect on the synchronization task. The mean blood pressure in Subliminal had a significant increase compared with that in Cnst and Supraliminal. These results indicate that subliminal fluctuation evokes sympathetic hyperactivity without affecting processing resources. Implementation of subliminal operation period into industrial machines performing periodic behavior might inhibit monotony and, therefore, prevent human error. [ABSTRACT FROM AUTHOR]