Study on the Possibility of Assessment of Alertness Using Subsidiary Behaviors
The aim of this study is to explore the possibility of assessment of alertness using subsidiary behaviors. Using the previous experimental data, 8 subjects’ subsidiary behaviors, which appeared during 3 monotonous VDU tasks, were picked up by 3 experimenters. These behaviors were classified into 13 categories according to their similarity. As a physiological index, electroencephalogram, which was known as the most sensitive index for measuring alertness, were measured. To investigate whether the number of these behaviors could be utilized for assessment of alertness, the following studies were carried out: 1) the relationships among the task performance, categorized behaviors and EEG were analyzed to make sure whether alertness had an impact on the task performance and the behaviors, 2) using the task performance, the level of alertness was classified tentatively, then the behaviors that were changed by the classified level of alertness were specified, 3) to testify the possibility of assessment of alertness, discriminant analysis were conducted using the above behaviors, and 4) quantification analysis III and cross correlation analysis were carried out to explore if the behaviors could estimate a decline of alertness before the performance deteriorated.As the results of the above 4 points, the following were suggested: 1) some subsidiary behaviors were influenced by alertness, to say nothing of performance, 2) regardless of individual differences, there were some behaviors that were changed by the level of alertness which was tentatively classified in this study, 3), the level of alertness at the point could assess using some behaviors, such as "rub, pinch, and scratch", "ease the stiffness", "postural adjustments", "movement of eye’s and mouth", "action of low alertness", and 4) some behaviors indicated the premonitory sign of a decline in alertness, the other increased when a decline in alertness had been observed. Also, depends on alertness, there were some stages about the appearance of the categorized behaviors. From these results, it was suggested that everyone could assess the level of workers’ alertness using subsidiary behaviors. Moreover, the results revealed that subsidiary behaviors were useful index to estimate a decline in alertness.