Figure 1.

Experimental design. A, Central starting position. The keypad was placed on the desk, aligned with the central fixation cross. Under this condition, right targets require rightward movements, and left targets require leftward movements. B, Left starting position. The keypad was placed to the left of the left target location, so both right and left visual field targets (left target shown) require rightward movement. C, Right starting position. The keypad was placed to the right of the right target location, so both right and left visual field targets (left target shown) require leftward movement.