Effects of responding hand and concurrent verbal processing on time-keeping and motor-implementation processes

Area of Science:

• Cognitive Psychology
• Neuroscience
• Motor Control

Background:

• Paced tapping involves both internal time-keeping and motor implementation processes.
• Concurrent cognitive tasks can interfere with motor performance.
• Understanding the dissociation between timing and motor execution is crucial.

Purpose of the Study:

• To investigate how concurrent verbal processing affects time-keeping and motor implementation in paced finger tapping.
• To determine if interference effects differ between the left and right hands.
• To explore the neural basis of time-keeping mechanisms in motor control.

Main Methods:

• Two experiments involving concurrent verbal processing tasks during left and right index finger tapping.
• Analysis of intertap interval variability, separating time-keeping and motor implementation components.
• Comparison of interference effects across hands and variability components.

Main Results:

• Concurrent verbal processing increased variability in the time-keeping mechanism, but not motor implementation.
• Motor implementation variability was consistently lower for the right hand compared to the left hand.
• Verbal interference effects were equivalent for both the left and right hands.

Conclusions:

• A clear dissociation exists between internal time-keeping and motor implementation mechanisms.
• A single, shared time-keeping mechanism likely serves both hands.
• The left hemisphere plays a significant role in the time-keeping circuit for right-handers, irrespective of the tapping hand.