State anxiety disorganizes finger movements during musical performance.

Skilled performance, in many situations, exposes an individual to psychological stress and fear, thus triggering state anxiety and compromising motor dexterity. Suboptimal skill execution in people under pressure affects the future career prospects of trained individuals, such as athletes, clinicians, and musicians. However, it has not been elucidated in what manner state anxiety affects multijoint movements and thereby degrades fine motor control. Using principal component analysis of hand kinematics recorded by a data glove during piano performances, we tested whether state anxiety affects the organization of movements of multiple joints or merely constrains the amplitude of the individual joints without affecting joint movement coordination. The result demonstrated changes in the coordination of movements across joints in piano performances by experts under psychological stress. Overall, the change was characterized by reduction of synergistic movements between the finger responsible for the keypress and its adjacent fingers. A regression analysis further identified that the attenuation of the movement covariation between the fingers was associated with an increase in temporal error during performance under pressure. In contrast, neither the maximum nor minimum angles of the individual joints of the hand were susceptible to induced anxiety. These results suggest that degradation of fine motor control under pressure is mediated by incoordination of movements between the fingers in skilled piano performances. NEW & NOTEWORTHY A key issue in neuromuscular control of coordinated movements is how the nervous system organizes multiple degrees of freedom for production of skillful motor behaviors. We found that state anxiety disorchestrates the organization of finger movements so as to decrease synergistic motions between the fingers in musical performance, which degrades fine motor control. The findings are important to shed light on mechanisms underlying loss of motor dexterity under pressure.