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Figure 1: Test material of the different MI tasks. (a) Nine-Hole Peg Test. Participants were required to physically/mentally remove each of the 9 pegs from the holes and put them into the depression. (b) Visualization of the two-dimensional neurofeedback display. The location of the blue shape signaled the hand to be used for MI, and the ball represented the neurofeedback signal. The horizontal ball position is determined by the classification of MI contralateral versus ipsilateral, and the vertical ball position is determined by the classification of contralateral baseline versus contralateral MI. (c) Example stimuli from the limb lateralization task. Left-hand, right-hand, left-foot, or right-foot pictures were presented from varying angles, and participants had to judge their laterality.