Journal of Speech and Hearing Research Vol.21 563-579 September 1978.
© American Speech-Language-Hearing Association
A Laterality Effect in Isometric and Isotonic Labial Tracking
Harvey M. Sussman
John R. Westbury
University of Texas, Austin
Hemispheric dominance for sensorimotor control of lip activity was investigated by use of a pursuit auditory tracking task. This task involves continuous frequency matching of a computer-generated target tone and a subject-controlled cursor tone. Thirty right-handed subjects were tested under isometric lip and hand control, and 20 right-handed subjects under isotonic lip control. Subjects tracked 10 1-min trials under each laterality condition—cursor/right ear, target/left ear, and vice versa. In both experiments tracking performance was better when the lip-controlled cursor tone was presented to the right ear (hence direct contralateral route to left hemisphere). A significant (p < 0.05) cursor/right-ear advantage was found under isometric hand-tracking. Analysis routines examined relative laterality advantages across several time intervals within each 1-min trial. Consistent lateralization scores in favor of cursor/right-ear presentations (REAs) were independent of the time interval measured. For isometric tracking, 58% of subjects having laterality advantages (p < 0.10) revealed REAs. For isotonic tracking, 71% of subjects revealed REAs. Implications of the latter finding are discussed relative to a left hemisphere mechanism specialized to integrate movement-generated auditory feedback with dynamic kinesthetic information from the articulators.
Copyright © 1978 by the American Speech-Language-Hearing Association.