MANUAL ASYMMETRIES AND SACCADIC EYE-MOVEMENTS IN RIGHT-HANDERS DURINGSINGLE AND RECIPROCAL AIMING MOVEMENTS

Two experiments examined the coordination of eye and hand movements in right-handed subjects who completed single (Experiment 1) and recipro cal (Experiment 2) aiming movements with each hand. In both experiment s eye movements preceded hand movement, and arrived well in advance of the hand to allow pickup of visual information about relative positio n of the hand and target to correct te ongoing movement. With reciproc al aiming differences emerged between the hands. A right hand advantag e was found for movement execution, and a left hand advantage for move ment initiation. Manual asymmetries were not due to practice differenc es between hands. Subjects made larger initial saccades and more corre ctive saccades when aiming with the left hand. The pattern of eye-hand coordination was consistent with Woodworth's (1899) two component mod el of limb control, and at odds with models of limb control which sugg est that online visual pickup is of minor importance.