Mutual interactions between speech and finger movements.

Speech output and finger movements were recorded as right-handed males repeated a syllable while making cyclical finger movements in three experimental conditions: (2) maintaining constant amplitude in both response systems; (b) alternating speech amplitude while attempting to maintain constant finger movement amplitude; and (c) alternating finger movement amplitude while attempting to maintain constant speech amplitude. Observations showed that output of the two response systems was coupled (one syllable was uttered with each finger movement) and entrained in amplitude (the amplitude pattern of the response that the subject attempted to keep constant followed that of the concurrently-active amplitude-modulated response). These interactions were bidirectional and were present with both left-handed and right-handed finger movements. The interactions are more extensive and subtle than mere interference wtih one response system by the other, and apparently do not depend on anatomical overlap of the responding neural systems.