Figure 3From: (C)overt attention and visual speller design in an ERP-based brain-computer interfaceMean counting accuracy for the Matrix and the Hex-o-Spell in the two attention conditions. Error bars show 1 SEM. Counting accuracy was higher for the Hex-o-Spell than for the Matrix, and higher for overt attention than for covert attention. The performance drop from overt to covert attention was more severe for the Matrix than for the Hex-o-Spell.Back to article page