Jaw and finger movement accuracy under visual and nonvisual feedback conditions.

The present study revisited the issue whether the presence of added visual feedback differentially affects the accuracy of finger and jaw movements. 15 men were instructed to move either the index finger on the dominant (right) hand, or the jaw, to a predefined target position with the highest precision possible. During execution of the task, on-line visual feedback of the moving articulator was either present or removed. In contrast to previous findings, significant improvement was observed for both finger and jaw movements in the visual feedback condition. Movement error in the nonvisual condition was proportionally greater for finger than for jaw movements which may have reflected a speed-accuracy trade-off because finger movements in the nonvisual condition were executed significantly faster than those of the jaw. The present findings support the beneficial effects of adding visual feedback during dynamic oral and finger movements that require a high spatial precision. Such findings support current methods of clinical intervention in speech-language pathology anl other disciplines. Furthermore, the results contribute to our understanding of the role of various modalities of feedback during motor execution.