Fig. 2: The results of the Experiment 1.

A Box plots of the keypress error across the skilled pianists who underwent the repetition training of the experimental task in the pretest and posttest sessions. The x-axis and y-axis indicate the session and the keypress error, respectively. There was no significant difference between the pretest and posttest, which confirmed no training effect of repeating the experimental task. B Box plots of the keypress error in the pretest and posttest sessions for the skilled FB (black), no-FB (red), and non-skilled FB (blue) groups. The x-axis and y-axis indicate the session and the keypress error, respectively. A horizontal line indicates a significant difference between the pretest and posttest in the group of the same color (P < 0.05). C Box plots of the timing error of each of the two movement patterns (A, B) across 10 blocks in the skilled FB (black), no-FB (red), and non-skilled FB (blue) groups. The x-axis and y-axis indicate the block and the timing error, respectively. Asterisk and hashtag indicate significant differences in the timing error between the FB group and each of the no-FB and non-skilled FB groups, respectively. D Box plots of the timing error of each of the two movement patterns (A, B) in pretest and posttest sessions in the skilled FB (black), no-FB (red), and non-skilled FB (blue) groups. The x-axis and y-axis indicate the session and the timing error, respectively. The timing error derived from the experimental task was higher for the movement pattern B compared with the movement pattern A (P < 0.05), which indicates higher difficulty of executing the movement pattern B. Twenty-four right-handed skilled pianists (12 for each group) and 12 right-handed age-matched non-skilled pianists participated in the Experiment 1.