Table 5. Comparison of Classification Accuracy in Different Frequency Bands With and Without Feature Selection Base on Coherence.

Coherence	Without feature selection	With Feature selection
	Mean (S.D.)	Mean (S.D.)	p
Theta	0.46 (0.03)	0.55 (0.03)**	7.38×10−29
Alpha	0.44 (0.03)	0.54 (0.03)**	4.15×10−32
Beta	0.40 (0.02)	0.53 (0.04)**	1.64×10−46
Gamma	0.40 (0.04)	NS

Note: NS: No couples of electrodes were selected since there was no main effect among emotional states (i.e. no feature selection was performed);

**Accuracy with feature selection is significant higher than that without feature selection, p<.01.