Aligned bow position profiles (x_s) recorded on the Test Violin and the Test Violinist’s Personal Violin, during playing by the Test Violinist. Columns correspond to distinct musical excerpts. Black curves denote the “Before” phase and gray curves denote the “After” phase. The bottom panel displays the mean bow position difference between the “After” and the “Before” phases. Shaded bands indicate the 95% confidence interval across repeated takes (N = 3 for the “Before” phase, N = 2 for the “After” phase).