. 2022 Apr 26;22(9):3331. doi: 10.3390/s22093331

Table 2.

Additional different categorization of the BCIs in the literature by Pasqualotto et al. [23], Machado et al. [26], Padfield et al. [2] and Nicolas-Alonso and Gomez-Gil [27].

Author	BCI Categorization	Description
Pasqualotto et al. [23] Machado et al. [26]	Dependent	Dependent on muscles and peripheral nerves. For example, in case of visual evoked potential (VEP), gaze is directed by muscles to focus on different visual stimuli.
Pasqualotto et al. [23] Machado et al. [26]	Independent	Muscle movement is not needed to control BCI. For example, in case of P300 response is detected from EEG and analyzed.
Padfield et al. [2]	Evoked	Also named as exogenous. Some type of external stimulation is required such as visual, auditory, or sensory. Can be further divided to evoked potentials and event-related potentials. In case of evoked potentials, changes in EEG can be detected due to responses to external stimuli. In case of event-related potentials, the changes in EEG are caused by sensory or cognitive events.
Padfield et al. [2]	Spontaneous	Also named as endogenous. External stimulation is not required. For example, motor-imagery technique, where subjects imagine movement of a limb and there is no additional input from external stimuli.
Nicolas-Alonso and Gomez-Gil [27]	Synchronous	The BCI analyzes signals during certain time windows, and the subject is able to give commands after fixed time intervals.
Nicolas-Alonso and Gomez-Gil [27]	Asynchronous	The brain waves of the subject are analyzed constantly, and the subject can give commands whenever the subject wants. Asynchronous BCI gives the subject more possibilities and flexibility concerning controlling the BCI.