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

Table 5

VAS fatigue and NASA-TLX scores (mean ± SE), including six different dimensions such as mental demand, physical demand, temporal demand, effort, performance, and frustration.

Parameters	Overt attention				Covert attention
	Small	Medium	Large	Mean	Small	Medium	Large	Mean
VAS fatigue	4 ± 0.6	2.8 ± 0.7	4.5 ± 1	3.8 ± 0.5	5.42 ± 0.7	4.8 ± 0.7	5.3 ± 0.8	5.2 ± 0.2
Total workload	40.4 ± 7.2	38.22 ± 4.8	41.2 ± 6.4	39.9 ± 0.9	65.1 ± 5.4	60.4 ± 6.4	66.9 ± 4.9	64.1 ± 1.9
Mental demand	9.9 ± 2.8	11.7 ± 2.9	12.5 ± 2.7	11.4 ± 0.8	16.7 ± 2.6	16.8 ± 2.7	18.0 ± 3	17.2 ± 0.4
Physical demand	3.8 ± 2.1	4.2 ± 1.7	6.3 ± 2.3	4.8 ± 0.8	6.9 ± 2.7	3.31 ± 1.1	6.39 ± 1.9	5.5 ± 1.1
Temporal demand	7.3 ± 1.3	9.2 ± 1.8	6.8 ± 1.8	7.8 ± 0.7	13.2 ± 2.9	9.6 ± 1.9	13.4 ± 2.4	12.1 ± 1.2
Effort	9.5 ± 2.7	7.9 ± 1.7	7.5 ± 1.8	8.3 ± 0.6	13.3 ± 2.3	13.4 ± 2.1	14.7 ± 2.4	13.8 ± 0.4
Performance	4.8 ± 1.8	3.8 ± 1.6	8.6 ± 2.7	5.7 ± 1.5	10.1 ± 1.8	13.6 ± 3.3	7.61 ± 1.9	10.4 ± 1.7
Frustration	4.8 ± 2.3	1.2 ± 0.7	3.5 ± 1.2	3.2 ± 1.1	4.95 ± 2.5	3.3 ± 1.1	6.78 ± 2.0	5.01 ± 1