Abstract
In this study, psychological, physiological and behavior measurements were
conducted before, during and after long driving sessions on public roads. The data obtained
were compared to examine changes in the driver´s functions due to physical and mental
fatigue, excluding sleepiness, caused by long driving. Two driving courses were used in the
experiments. One course mainly included expressways, and the other course consisted only of
urban roads. The driving time on each course was three hours or less. As psychological
indices, questionnaires consisting of 45 questions were used, and the subjects were asked to
answer all the questions every thirty minutes while driving. As physiological indices, saliva
was collected at the starting, middle and end points of the driving sessions, and the
concentrations of cortisol, secretory immunoglobulin A (s-IgA) and chromogranin A (CgA) in
the saliva samples were analysed. And as behavior indices, performance in a car-following
task on a proving ground and reaction time to the illumination of the lead car's brake lights
were measured before and after driving on public roads. Simple and selective reaction times
were also measured in laboratory tests. Furthermore, a Go/No-go task was used before and
after driving on the urban road course. In this task, the subjects had to judge on which side
(right or left) a stimulus was presented and whether they should respond to the stimulus or not.
The results showed that the variance of the following distance in the car-following task was
greater after a driving session than before it. The simple reaction time, selective reaction time
and rate of incorrect answers in the laboratory tests also increased after the driving sessions.
In the Go/No-go task, it was found that reaction time increased more on the opposite side of
the dominant hand than on the dominant hand side. This suggests the possibility that cerebral
hemispheric dominance may have some relation to changes in the driver´s state due to long
driving. Furthermore, the results of a correlation analysis showed that there was a rather high
correlation between feelings of "physical fatigue" and "listlessness/languor" and performance
in the car-following test and reaction time. It was also found that there was a relatively high
correlation between a feeling of "listlessness/languor" and the concentration of s-IgA in the
subjects' saliva.
Keywords - Long driving, Reaction time, Following distance, Saliva component,
Hemispheric dominance