Fig. 2

Different types of trials in the study. (a) Paradigm describing the sequence of events and sequence of the triggers’ labels used in a single trial for the Training and Feedback sessions. In these types of sessions, 20 questions with “yes” and “no” answers, known by the patient, are presented in a pseudo-random order. (b) Paradigm describing the sequence of events and sequence of the triggers’ labels used during a single trial for the Copy and Free spelling sessions. In these sessions, instead of questions, the patient is presented with options that allow him/her to navigate through his/her predetermined spelling scheme (e.g., sectors, letters). For both spelling sessions, the limit in the number of trials depends only on the patient’s attempts to spell the given target (i.e., Copy speller sessions) or her/his desired sentence (i.e., Open speller sessions). For any type of session recorded, the recording’s start and end are indicated by an “S 9” and an “S 15” trigger.