Five Shades of Grey: Exploring Quintary m-Sequences for More User-Friendly c-VEP-Based BCIs

Figure 1

Graphical user interface of the c-VEP-based eight-target speller. Each target corresponded to a lagged version of an m-sequence. By selecting a group of letters (e.g., H–N), a second layer containing individual letters was displayed. In the example, the letter K was selected. In addition to letter groups, the first layer of the interface also presented three word suggestions based on an integrated dictionary function. The lower right target represented an undo function. Feedback was given to the user by enlarging the selected target for 100 ms, voicing the corresponding letter, and adding it to the text output field in the centre of the screen.

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