Impact of Speller Size on a Visual P300 Brain-Computer Interface (BCI) System under Two Conditions of Constraint for Eye Movement
Table 7
Subjects’ distribution for each dimension.
Dimension
Overt attention
Statistics (Fisher’s exact test)
Covert attention
Statistics (Fisher’s exact test)
Rank
Small
Medium
Large
Small
Medium
Large
Favourite
1
6
3
3
F = 6.337;
5 (42%)
3 (25%)
4 (33%)
F = 13.715;
2
2
3
7
1 (8%)
3 (25%)
8 67%)
3
4
6
2
6 (50%)
6 (50%)
0 (0%)
Complex
1
1 (8%)
5 (42%)
6 (50%)
F = 13.715;
5
5
2
F = 4.042;
2
2 (17%)
6 (50%)
4 (33%)
3
5
4
3
9 (75%)
1 (8%)
2 (17%)
4
2
6
Comfortable
1
8 (67%)
0 (0%)
4 (33%)
F = 19.358;
7 (58%)
0 (0%)
5 (42%)
F = 13.577;
2
0 (0%)
9 (75%)
3 (25%)
1 (8%)
8 (67%)
3 (25%)
3
4 (33%)
3 (25%)
5 (42%)
4 (33%)
4 (33%)
4 (33%)
Stressful
1
6 (50%)
1 (8%)
5 (42%)
F = 13.715;
7
3
2
F = 7.359;
2
0 (0%)
8 (67%)
4 (33%)
1
6
5
3
6 (50%)
3 (25%)
3 (25%)
4
3
5
Controllable
1
6
2
4
F = 6.24;
4
4
4
F = 6.913;
2
1
6
5
1
6
5
3
5
4
3
7
2
3
Tiring
1
2 (17%)
3 (25%)
7 (58%)
F = 21.288;
4 (33%)
3 (25%)
5 (42%)
F = 10.804;
2
1 (8%)
9 (75%)
2 (17%)
1 (8%)
8 (67%)
3 (25%)
3
9 (75%)
0 (0%)
3 (25%)
7 (58%)
1 (8%)
4 (33%)
Percentages are indicated for those dimensions with significant differences. Ranks are ordered as follows: rank 1, the least; rank 2, intermediate; and rank 3, the most. Significant results have been denoted in bold.
