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. 2013 Oct 31;8(10):e77755. doi: 10.1371/journal.pone.0077755

Figure 1. Stimulus spatial organization in the P300 BCI comparing with the oddball paradigm.

Figure 1

(A) Visual oddball paradigm. (B) Matrix (“classical”) P300 BCI layout with stimuli grouped into rows and columns. (C) P300 BCI layout with fixed arbitrary stimulus positions and single-cell presentation mode (without grouping). (D) P300 BCI layout with moving stimulus positions and single-cell presentation mode (a design used in this study). S, standards (non-target stimuli). T, targets (target stimuli). In these examples, a flashing letter B is the target stimulus. Note that the content at the location that should be attended (marked with a red circle) significantly varies with sequential presentations in the oddball paradigm (A) (both targets and standards are presented there), whereas in the P300 BCI (B, C, D), the attended location can be in one of two states only (target stimulus on/off; the standards are presented at other locations).