FIGURE 1.

Finger position during 2D-angle discrimination (90° reference angle shown here). The angles were explored with the arm out-stretched using the distal phalanx of the index finger for exploration, the arm placed along the body, thus avoiding large shoulder or head movements. A single continuous to-and-fro movement was used by the subject to explore the angles during the stimulation block, following the sequence a-b-c-b-a (digit shown in the start position a here). The explored border was restricted to 3 cm on each surface, as delimited by plasticine markers placed just beyond the 3 cm point on either side of the intersection.