Using the double-step target displacement paradigm the mechanisms underlying arm trajectory modification were investigated. Using short (10- 110 msec) inter-stimulus intervals the resulting hand motions were initially directed in between the first and second target locations. The kinematic features of the modified motions were accounted for by the superposition scheme, which involves the vectorial addition of two independent point-to-point motion units: one for moving the hand toward an internally specified location and a second one for moving between that location and the final target location. The similarity between the inferred internally specified locations and previously reported measured end-points of the first saccades in double-step eye-movement studies may suggest similarities between perceived target locations in eye and hand motor control.
['Ealan A. Henis', 'Tamar Flash']
A Computational Mechanism to Account for Averaged Modified Hand Trajectories