Fig 1.
PRISMA flow diagram of hybrid BCIs.
Fig 2.
Flow diagram of taxonomy for hybrid BCIs.
Table 1.
The number of studies with each combination of biosignal.
Table 2.
Applications of each modality in hybrid BCIs.
Fig 3.
Schematic diagram for three different roles of operation.
Table 3.
Classified hybrid BCI types according to the proposed taxonomy.
Fig 4.
PRISMA flow diagram of usability of BCI.
Table 4.
Classification of articles by task characteristics.
Table 5.
Classification of articles by evaluation tool of subjective measures.
Table 6.
Frequency of subjective measures used in the reviewed articles.
Table 7.
Frequency of performance measures used in the reviewed articles.
Fig 5.
Usability dimensions for BCI systems.