I did further data analysis about the average gesture pressure and gesture length. For these two features, I also used the normalisation to to eliminate the effect on the value from the target letter, e.g. the shape or the way to write that letter.
1. Pressure: The mean value indicates that the pressure tended to be larger in the high load session than the normal session, but the p-value is greater than 0.05, which means the differences between two sessions are not significant.
2. Gesture Length: in Lisa's paper, she noticed the significant effect of cognitive load on gesture length. In my analysis, I added the normalisation step, and the p-value is still less than 0.05. It means there is a significant differences between average gesture length in the high load session and normal session.
In the next stage, I'll do more analysis related to the gesture length, and try to come up with more features.