Investigating driver's distraction and mental workload under dual-task processing, and the effectiveness of auditory warning feedback in a realistic driving environment

• Main Authors: Chiu, Tien-Ting, 邱添丁
• Other Authors: Hsu, Shang-Hwa
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/10476234620820758483

博士 === 國立交通大學 === 工業工程與管理系所 === 98 === Driver distraction and inattention are important issues of driving safety. It easily leads to traffic accidents when drivers shift their attention away from the driving task. Based on this circumstance, we conducted two studies in a virtual reality driving environment to explore the effects on reaction time of driver distraction and workload, and auditory warnings. In first study, the aim was to discover how answering math equations affected driving workload and found out the relationship between responding to car deviation and answering math equations. The second study was aim to investigate what kind of warning sounds and frequency could effectively give a caution and prevent traffic accidents caused by inattentiveness during driving. In first study, we hypothesized that the stimulus onset asynchrony (SOA) affects dual-task (driving & cognitive task) performance. We measured and evaluated the dependent variables in two aspects, driving-related task and workload-related task. The response time (RT) for responding car deviation was a dependent variable of driving-related task. Other dependent variables of workload-related measures were RT of giving correct answers and the number of incorrect answers of arithmetic task. The total of 25 volunteer participants was in this study. This experiment demonstrated that the performance of driving task did not be affected by interruption of arithmetic task, the distraction effect did not occur. We also found that the mental workload for secondary task (cognitive task) was much higher than that for the primary task (driving task). Additionally, the study found that participants’ driving strategy in the dual-task conditions took the driving manipulation as a priority. The more attentional resources consumed by the primary task, the fewer there are for the secondary task. Therefore, the secondary task caused participants' cognitive load to be maximized. Reaction time on the secondary task is thus seen as an indicator of demanded attentional capacity amount of the primary task. In second study, we attempted to identify what kind of auditory warning signals and characteristics could maintain driving performance. The study was carried out under seven conditions: with no warnings, with continuous warning tones (500 Hz, 1,750 Hz, 3,000 Hz), and with tone burst (500 Hz, 1,750 Hz, 3,000 Hz). The conditions were examined in random order and we ran different experimental sessions for the different conditions. Besides, we designed a questionnaire to measure individual experiences subjectively. To assess influence of stimulus characteristics on improvement in driving performance, this study conducted a test based on two-way ANOVA (type of sounds × carrier frequency, CF). The total number of volunteers was 13 participated in this study. The experiment result indicated that the mean response time (RT) of the warning sessions was also significantly less than for the without-warning sessions. Comparing the effectiveness of varying carrier frequency on RT, continuous tone, two sound frequencies, 1,750 and 3,000 Hz, were more effective in accelerating driver’s reaction time than the frequency of 500 Hz. In addition, more than 92% of the participants agreed with the statement that tone burst type warning sound gave efficacious warning. Also 92% of al1 respondents agreed that the warning sound frequency of 1,750 Hz (69%) and 3,000 Hz (23%) had better effectiveness. Based on the result of these two studies, the cognitive tasks could not significantly affect the performance of any assessed driving tasks. And the spectral characters in terms of the carrier frequency (CF) significantly influenced the warning effectiveness. Hence, the mental workload, driver’s distraction, and traffic safety are intrinsically intertwined. To reduce injury caused by driver’s distraction, fatigue, inattention, and mental load, we need to develop a real-time detection warning system of dual-task and driver’s drowsiness. It would combine design elements of human interface technology and brain-computer interface, and take into consideration the driver and their capabilities in the driving environment.