Voluntary manual exploration and vision in rod bisection

Two experiments were carried out to investigate contributions of voluntary manual exploration and vision to rod-bisection performance when the rod was placed in different spatial positions. Analysis showed both voluntary manual exploration and vision contributed to the accuracy of rod-bisection performance in healthy adults (Exp. 1:12 men, 13 women; Exp. 2:10 men, 11 women). Advantages of voluntary manual exploration were related to rod position and initial search direction. Results are discussed with regard to ecological approach to action and perception, two cortical systems (ventral and dorsal streams) for perception and control of actions, and the hemispheric activation hypothesis.