Impact of Speller Size on a Visual P300 Brain-Computer Interface (BCI) System under Two Conditions of Constraint for Eye Movement

Table 3

Error performance (%, mean ± SE) results of the online task for each participant.

Participant	Overt attention				Covert attention
	Small	Medium	Large	Mean	Small	Medium	Large	Mean
S1	16.7	0	41.7	19.4 ± 12.1	66.7	33.3	66.7	55.6 ± 11.1
S2	8.3	0	0	2.8 ± 2.7	83.3	41.7	50	58.3 ± 12.7
S3	0	0	41.7	13.9 ± 13.9	16.7	16.7	8.3	13.9 ± 2.8
S4	0	8.3	8.3	5.6 ± 2.8	16.7	66.7	41.7	41.7 ± 14.4
S5	0	0	8.3	2.78 ± 2.8	50	25	33.3	36.1 ± 7.4
S6	0	33.3	0	11.1 ± 11.1	41.7	75	100	72.2 ± 16.9
S7	0	0	16.7	5.6 ± 5.6	75	58.3	66.7	66.7 ± 4.8
S8	0	0	0	0 ± 0	25	25	33.3	27.8 ± 2.8
S9	0	8.3	25	11.1 ± 7.4	25	25	100	50 ± 25
S10	8.3	0	33.3	13.9 ± 10	33.3	75	58.3	55.5 ± 12.1
S11	0	8.3	8.3	5.6 ± 2.8	50	75	75	66.7 ± 8.3
S12	0	0	8.3	2.8 ± 2.8	66.7	8.3	66.7	47.2 ± 19.5
Mean	2.8 ± 1.6	4.9 ± 2.8	16.0 ± 4.5	7.87	45.83 ± 6.7	43.75 ± 7.2	58.33 ± 7.8	49.3