Temporal and force characteristics of fast double-finger, single-finger and hand tapping.

The purposes of this study were: (1) to provide descriptive temporal and force data for fast alternate tapping by the index and middle fingers ('double-finger mode'), and to compare it with one finger fast tapping ('single-finger mode'); (2) to determine any differences in the dynamic motor function of individual fingers with these tapping tasks; and (3) to determine any differences between the single-finger mode and tapping with the whole hand ('hand mode'). Eleven healthy males tapped force transducer(s) for 7 s as fast as possible using their dominant hand. The double-finger mode had a greater peak force and a 50% faster tapping frequency than the single-finger mode. There was no correlation between the single-finger and double-finger modes in the temporal data. Tapping with two fingers thus seems to be organized with a motor strategy that is different from that with one finger, and can possibly capture an individual's additional or different motor function. A comparison between the two fingers revealed that the index finger had a significantly faster tapping frequency, indicating the superiority of the index finger over the middle finger in terms of dynamic motor function. The hand mode had a significantly faster tapping frequency with greater peak force than the single-finger mode. A distinction is essential between these two modes.