Figure 2

Virtual line bisection. Top: In the normal condition, the haptic device controls the pencil. When the pencil is lift up, the stroke is replaced by a cross if the stroke intersects the line. The subject can retry or validate his bisection and move on to the next trial. Bottom left: a montage showing the center of the lines (red crosses) in the three conditions (left sided, centered and right sided) and the extents of the lines when centered (in black). Bottom right: a montage showing the virtual line bisection in the reduced visual condition. The virtual world is viewed through a moving hole (only the bright area is visible). The subject has to stop the moving hole when the green cross reaches the middle of the line. When a choice is made, the whole virtual world is displayed. The subject can retry or validate and move on to the next trial.