CHARACTERIZATION OF POWER SPECTRAL DENSITY AND INDIVIDUAL ALPHA FREQUENCY OF EEG SIGNALS WITH A STIMULI OF SIMPLE ARITHMETIC TASKS

• Main Author: Aziezah, Fithriyyah
• Format: Theses
• Language: Indonesia
• Subjects: Fisika
• Online Access: https://digilib.itb.ac.id/gdl/view/41367
• Institution: Institut Teknologi Bandung

Arithmetic questions are often used to find out someone’s mathematical abilities. This questions can also be used in the psychological testing process as a stimulus for certain conditions, one of which is cognitive fatigue. Cognitive fatigue is a condition caused by monotonous work which involving cognitive function in a long period that influences performance impairment. One of the methods to generate cognitive fatigue is using calculation of power spectral density (PSD) and Individual Alpha Frequency (IAF) of brain waves which was obtained from an electroencephalography (EEG) measurement. This study aimed to calculate PSD and IAF towards stimuli of cognitive tasks in the form of simple arithmetic question at electrode located in the frontal, parietal, and occipital lobes. The EEG was measured by using Cadwell Easy R III with a sampling frequency of 250 Hz and the electrode impedance maintained below 20 kW. Electrodes on F3, F4, F7, F8, Fz, P3, P4, O1, and O2 were investigated in this study. The data acquisition was conducted to 9 adult subject within 46 minutes: 3 minutes before, 40 minutes during, and 3 minutes after carrying out test. The arithmetic test was displayed through the visual display terminal (VDT). In the next stage, the pre-processing was conducted to remove noise and artifacts, followed by PSD calculation using the Welch periodogram. Finally, the values of IAF were calculated by using the Center of Gravity (CoG). The results showed that the PSD in all sessions were sorted from the largest values of the delta, theta, and alpha waves, with the value of the left hemisphere greater than the right hemisphere, and the PSD value in the low wave increased in accordance with the high wave. As for the IAF pre-task values shifted towards larger alpha frequency in the post-task in frontal and parietal region, showed in vigilance with increasing time spent on task, and shifted towards smaller values in occipital region which fatigue begins to occur in this region and has not occured in other region