Timing at peak force may be the hidden target controlled in continuation and synchronization tapping

Area of Science:

• Neuroscience
• Motor Control
• Human Movement Science

Background:

• Timing control in movement, including rate production and synchronization, is crucial for motor tasks.
• Finger-tapping tasks commonly measure timing at initial contact, but peak force timing is less explored.
• Peak force represents a distinct and potentially significant event in the finger-tapping motor sequence.

Purpose of the Study:

• To compare timing accuracy and variability between initial contact and peak force during finger tapping.
• To investigate the role of peak force timing in sensorimotor synchronization and continuation tasks.
• To determine if peak force timing is actively adjusted by participants.

Main Methods:

• Participants performed finger-tapping tasks under two conditions: continuation (tapping at a set rate after a metronome stops) and sensorimotor synchronization (tapping in time with a metronome).
• Force sensors recorded tapping events, allowing measurement of timing at both initial contact and peak force.
• Analysis included timing accuracy, variability (central clock variability), statistical dependence (lag-one autocorrelation), and error correction (mean signed error).

Main Results:

• In the continuation task, timing accuracy and statistical dependence were similar for initial contact and peak force, but central clock variability was lower at peak force.
• In the synchronization task, peak force timing was more accurate and less variable than initial contact timing.
• Peak force error was actively corrected towards zero, while initial contact error was not, despite similar statistical dependence.

Conclusions:

• Timing at peak force is a significant target for motor timing control, especially during sensorimotor synchronization.
• The active correction of peak force timing may explain the typically negative signed error observed at initial contact in previous studies.
• These findings highlight the importance of considering different phases of a movement, like peak force, in understanding motor timing.