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Fig. 9.15
Slope criterion
summed over all electrodes
for each of 13 participants
x
10
9
1
0.5
0
−0.5
−1
normal state
relaxed state
−1.5
−2
0
2
4
6
8
10
12
14
Participant number
Fig. 9.16
Slope criterion
summed over all participants
for each of 58 electrodes
2
x
10
8
0
−2
−4
−6
normal state
relaxed state
−8
−10
0
10
20
30
40
50
60
Electrode number
relaxation. Thus, the slope criterion can effectively discriminate the two states of
alertness for an individual. However, a strong inter-individual variability can be
observed in Fig.
9.15
. Because of this strong individual variability, we cannot plot a
line on Fig.
9.15
which separates the two alertness states (represented by cross and
circles). Then, for a given subject with two EEG records, the slope criterion allows
determining which record corresponds to the record done in the relaxed state.
However, when only one record is known (new subject), we cannot classify it
effectively.
