The authors investigated the effects of the operation of a cellular telephone and conversing through a cellular telephone while driving on a driver's mental workload (MWL). The driver's MWL was measured by the NASA Task Load Index (NASA-TLX). The cellular telephone was equipped with a handsfree device. The experiment was conducted on an expressway in Japan. Sixteen male subjects participated in the experiment. Half of the subjects had experience in using a cellular telephone while driving. Each subject was asked to follow a leading vehicle and to maintain a constant distance behind the vehicle. The subjects performed three tasks: following a leading vehicle, operating a cellular telephone while driving, and talking with the experimenter through a cellular telephone while driving. After the experiment, each subject provided ratings on six subscales in terms of MWL. Overall workload (OW) was estimated by combining the six rating values. ANOVA was performed on the driver's MWL. The operation and talking through a cellular telephone had little effect on MWL in the case of subjects who had experience using a cellular telephone. For the subjects who had no experience in using a cellular telephone, the tasks of operating and talking through a cellular telephone while driving had significant effects on the driver's MWL. (A)
Samenvatting