Robotic hand helps pianists overcome “ceiling effect”

A helping robot hand

A total of 118 pianists participated in three different experiments. In the first, 30 pianists performed a designated "chord trill" motor task with the piano at home every day for two weeks: first simultaneously striking D and F keys with the right index and ring fingers, then striking the E and G keys with the right middle and little fingers. "We used this task because it has been widely recognized as technically challenging to play quickly and accurately," the authors explained. It appears in such classical pieces as Chopin's Etude Op. 25. No. 6, Maurice Ravel's "Ondine," and the first movement of Beethoven's Piano Sonata No. 3.

Hand exoskeleton robot attached to the digits of the right hand. The device can flex and extend the metacarpophalangeal joints of the individual digits. Credit: Shinichi Furuya

The pianists performed the task at a tempo of 80 BPM for ten seconds, followed by a ten-second rest for 30 sessions. After two weeks, they were assigned to one of two laboratory groups, in which the robot exoskeleton hand passively moved those four fingers for 30 minutes to perform the chord trill—faster than the players could do so themselves. This was followed by a post-test session in which the pianists played the chord trill twice for five seconds, as quickly and accurately as possible. The second experiment was designed to pinpoint the elements of movement that led to the enhanced motor skills, involving 60 pianists randomly assigned to one of five groups and getting different interventions.

The results: "Even when the skill plateaued after weeks of piano practice, passive training of the fast and complex motor skill with the robot further facilitated the maximum rate of repetitive piano keystrokes involving fast and complex multifinger movements," the authors wrote, and the training effect also showed up in the untrained hand, so there was an "inter-manual transfer effect." In other words, the hand exoskeleton allows "skilled individuals achieve otherwise impossible motions," and is thus an effective way to overcome the ceiling effect.

A third experiment aimed to assess any changes in neuroplasticity in the corticospinal system during passive training. This involved 28 pianists undergoing the same lab-based protocol as the first experiment while undergoing electromyographic (EMG) monitoring, and stimulated regions of the motor cortex associated with finger movements before and after training sessions. Only the hand trained by the exoskeleton showed pattern changes in multifinger movements, which the authors suggest is evidence of neuronal adaptation from the passive training. More research is needed into why the untrained hand also showed improved motor skills.

The authors acknowledge that participants were limited by the risk of muscular fatigue. For instance, one experiment involved five trials in which pianists played as fast as they could at the maximum rate for ten seconds, but players found it difficult to do so for longer periods, or for more than ten trials. Still, the authors believe their study "highlights the importance of embodying otherwise impossible skills using augmentation technology such as a robotic exoskeleton." It could also prove useful for rehabilitation of certain neurological disorders that affect manual dexterity.

DOI: Science Robotics, 2025. 10.1126/scirobotics.adn3802 (About DOIs).