Table 3.
Measured metrics of the physiological parameters.
| Parameter | Metric | Implication |
|---|---|---|
| ECG | SDNN (ms) | Standard deviation of NN interval time series |
| RMSSD (ms) | Root mean square of successive differences between normal heartbeats | |
| pNN50 (%) | Percentage of successive RR intervals that differ by more than 50 ms | |
| EEG | Alpha relative power | Inability to focus, relaxation (8–13 Hz) |
| Beta relative power | High arousal, stress (14–30 Hz) | |
| Theta relative power | Drowsy, depression (4–7 Hz) | |
| Delta relative power | Extreme fatigue, deep sleep (1–3 Hz) | |
| Eye movements | Fixation duration (ms) | The sum of time the eyes remain fixated on each fixation point in the task scene region |
| Saccade amplitude (px) | The distance from the end of the last fixation to the beginning of the next fixation in pixels | |
| Saccade velocity (px/ms) | The average distance per second between fixation points, defined as the saccade amplitude divided by the saccade time | |
| Mean pupil diameter (px) | The average diameter of left and right pupil |