Hand markers and joint angles.

<p>Twenty-five markers were placed on the fingers, hand, and forearm with corresponding labeling (top). Schematic of the calculation of individual joint angles: surface normals and angles (bottom).</p

Individual joint contributions to fingertip motion.

<p>Individual joint contributions (estΔTIP_DIP, estΔTIP_PIP, estΔTIP_MCP, estΔTIP_WRIST) to vertical fingertip motion for finger 2 plotted as a proportion of the actual vertical fingertip movement from time of maximum height to key bottom (ΔTIP) for all pianists (mean) and the two individuals S17 and S24. Error bars indicate standard error of the mean.</p

Temporal Control and Hand Movement Efficiency in Skilled Music Performance

<div><p>Skilled piano performance requires considerable movement control to accomplish the high levels of timing and force precision common among professional musicians, who acquire piano technique over decades of practice. Finger movement efficiency in particular is an important factor when pianists perform at very fast tempi. We document the finger movement kinematics of highly skilled pianists as they performed a five-finger melody at very fast tempi. A three-dimensional motion-capture system tracked the movements of finger joints, the hand, and the forearm of twelve pianists who performed on a digital piano at successively faster tempi (7–16 tones/s) until they decided to stop. Joint angle trajectories computed for all adjacent finger phalanges, the hand, and the forearm (wrist angle) indicated that the metacarpophalangeal joint contributed most to the vertical fingertip motion while the proximal and distal interphalangeal joints moved slightly opposite to the movement goal (finger extension). An efficiency measure of the combined finger joint angles corresponded to the temporal accuracy and precision of the pianists’ performances: Pianists with more efficient keystroke movements showed higher precision in timing and force measures. Keystroke efficiency and individual joint contributions remained stable across tempo conditions. Individual differences among pianists supported the view that keystroke efficiency is required for successful fast performance.</p> </div

Keystroke efficiency.

<p>Mean efficiency η by tempo condition for all pianists and two individuals S17 and S24. Error bars indicate standard error of the mean.</p

Fingertip position predicted by joint angles.

<p>Standardized regression coefficients of multiple regression models predicting each fingertip trajectory (4) from the five joint angle trajectories within tempo condition, plotted by finger and tempo condition.</p

Two keystrokes produced by different pianists.

<p>Stick figure display of a finger-3 keystroke for subjects 17 (top) and 24 (bottom) viewed from a side perspective. The individual lines represent equally spaced time slices from time of maximum height (blue) to key bottom (dark red).</p

Motion capture setup and marker placement.

<p>The motion capture setup involved 6 infrared cameras arranged around the digital piano (top). Fifteen markers were placement on the keyboard with the dimensions sketched in red (bottom).</p

Joint angle simulation.

<p>Individual joint angle contributions to simulated fingertip motion from maximum height (mxH in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0050901#pone-0050901-g001" target="_blank">Figure 1</a>) toward key bottom. Black dots indicate the marker position at time of maximum height above keyboard. For each of the four joint angles of the index finger (DIP blue, PIP green, MCP red, WRIST purple), we show the simulated fingertip movement for joint angles ranging from –45° (extension) to 45° (flexion) in steps of 5° with the assumption that only that particular joint contributes to the movement (all other joint angles unchanged).</p

Finger height and phase plane plots of velocity-acceleration trajectory for a pianist's Finger 1 (thumb) movement in the <i>attack</i> and <i>keypress</i> event region (see <b>Figure 2</b>).

<p>Black filled circles mark the end of movement, corresponding to full key pressure.</p

Movement of Finger 1 (thumb) during one pianist's performance of the notated melody at Slow tempo.

<p>Framed notes represent keypresses for Finger 1; vertical lines indicate the time at which the piano keys reached the bottom for each note in the melody. Highlighted regions underscore motion <i>attack</i> regions (dark gray areas) and <i>keypress</i> regions (light gray areas). Key height at rest was approximately 10 mm (+/− 0.5 mm).</p