- • Fail to provide written consent (Appendix 2C).
- • Fail to meet the requirements mentioned in inclusion criteria.
Sample Size Calculation
The minimum sample size was calculated using the statistical methods implemented in the PS (Power and Sample Size) software package and the computed sample size to achieve significant results in this study was 22 participants. The details of sample size calculation are briefly explained in Appendix 13A.
Data collection was performed in a temperature-controlled environment (20-25°C) and a simulator-based driving environment was developed for the data acquisition. This study was conducted in collaboration with the MIROS and the driving simulator was provided by MIROS for the data acquisition. The data acquisition setup is shown in Fig. 13.2. The study protocol is presented in Fig. 13.3. The total time for the data collection of each participant was 3-4 hours, including signing of consent form, measuring blood pressure (BP), questionnaire completion, calibration of physiological data acquisition device, head measurement, and driving tasks. The whole experiment was performed on the same day for each participant.
The experiment consisted of five sessions: (1) preexperiment session, (2) familiarization drive (FD) session, (3) training drive (TD) session, (4) monotonous drive (MD) session, and (5) postexperiment session. In
Figure 13.2 Experimental setup.
Figure 13.3 Experimental protocol.
the preexperiment session, the participant’s BP was measured. Additionally, each participant had given consent for the study to be performed and the participants were asked to complete a questionnaire related to drowsiness and mental states (see Appendix-13B). The next session was FD, in which participants drove the simulator-based car for 5-10 minutes. In this session, the participant was not wearing the physiological data acquisition device and the main aim was for the participant to familiarize themselves with the simulator, i.e., the road scenario, the force required to press the brake and the accelerator, and how to control the steering wheel. This session was followed by the TD session, in which the participant was wearing the data acquisition device and was allowed to drive for 10 minutes. This session mainly focused on getting the participant to feel comfortable with the EEG and ECG data acquisition device while driving.
Additionally, the participant was allowed to terminate the experiment if he/she experienced any issue such as headache, motion sickness, or physical sickness at any stage during data collection. The next session was the MD session, where the driver was asked to drive for 80 minutes. The driving scenario in this session was similar to driving on a highway in which there were no traffic signals and a very limited number of cars on the road. The vehicle speed was kept up to 80 km/hour to create a monotonous driving environment. Studies conducted in Refs. 16,17 showed that the time on task, nature of task, and vehicle speed are very important for getting drowsiness data. The last session was the postexperiment session, in which questions related to drowsiness, mental state, and the driving experiment were asked.
Each participant was instructed to follow these experiment day precautions:
- • Avoid usage of any kind of hair oil and gel on your head on the experiment day.
- • Avoid any type of alcoholic drink 24 hours prior to the experiment.
- • Avoid any type of caffeinated drinks (e.g., tea, coffee) 4 hours before starting the experiment.
- • Avoid any kind of energy/carbonated drink 4 hours before starting the experiment.
- • Avoid smoking 4 hours before starting the experiment.