Hand position as a variable determining the accuracy of aiming movements

Two experiments investigated the effect of hand position on the accuracy of short- and long-duration aiming movements in the presence and absence of visual feedback. Ss were 24 male right-handed university students. In Exp I, short aiming movements were executed rapidly, which would require them to be predominantly programmed; in Exp II these movements were performed slowly enough so that visual feedback could be used. The short-duration, short-length movements of Exp I were not appreciably disrupted by the removal of visual feedback, which implies that they were predominantly programmed. However, the long-duration, short-length movements of Exp II were disrupted when visual feedback was removed, which suggests that these movements were being guided by visual feedback. Having the heel of the responding hand in contact with the target platform during the response resulted in greater accuracy than did no hand contact for the short-length movements of both experiments. These results indicate that hand contact produces greater aiming accuracy than no hand contact for both programmed and feedback-based movements. (10 ref)