Interfinger Synchronization Capability of Paired Fingers in Discrete Fine-Force Control Tasks

This study examined whether within-a-hand and between-hands finger pairings would exhibit different interfinger synchronization capabilities in discrete fine-force control tasks. Participants were required to perform the designed force control tasks using finger pairings of index and middle fingers on one or two hands. Results demonstrated that the delayed reaction time and the timing difference of paired fingers showed a significant difference among finger pairings. In particular, paired fingers exhibited less delayed reaction time and timing difference in between-hands finger pairings than in within-a-hand finger pairings. Such bimanual advantage of the pairings with two symmetric fingers was evident only in the task types with relatively high amplitudes. However, for a given finger pairing, the asymmetric amplitude configuration, assigning a relatively higher amplitude to either left or right finger of paired fingers, has no significant effect on the interfinger synchronization. Therefore, paired fingers on both hands showed a bimanual advantage in the relatively high force, especially for the pairing of symmetrical fingers, whereas asymmetric amplitude configuration for a finger pairing was able to suppress the bimanual advantage. These findings would enrich the understanding of the interfinger synchronization capability of paired fingers and be referential for interactive engineering applications when leveraging the interfinger synchronization capability in discrete fine-force control tasks.