Visually-controlled leg movements embedded in a walking task

Accurate control of alternating leg movements in walking was considered as a visually controlled target aiming task. Nine subjects aimed alternate feet at targets along a walkway, using nine combinations of amplitude and target width giving index of difficulty values between 2.59 and 6.16. Movement time was compared to the same subjects performing reciprocal tapping tasks with arm and leg. Alternating target aiming tasks were the most rapid of all tasks studied. Explanations of this effect in terms of learning and elimination of direction changes were consistent with the data from all conditions. Visual control can be expected in normal walking only for target sizes smaller than about 300 mm, i.e., under unusual accuracy requirements.