A closed-loop, music-based brain-computer interface for emotion mediation - Fig 4

BCI study experiment protocol (A) and trial structure (B). (A) Each session began with a questionnaire, followed by a calibration phase and subsequent modeling of the emotion classifier. Afterwards, the main part of the experiment, the online application phase, was conducted. The experiment ended with a second questionnaire. (B) A single trial started with a resting period of 15 sec in which no music feedback was presented to the participant. The participant‘s EEG was recorded in the background, and the average score was used to assign, on every trial, one of the two tasks (modulate towards happy or sad) to the participant. The subject then performed the task for a duration of 30 sec (action period).