Preparatory slow brainpotentials occur prior to voluntary initiated movements (Bereitschaftspotenzial, BP) or between a warning (S1) and an imperative stimulus (S2) (contingent negative variation, CNV). Preparatory processes are of fundamental importance for effective motor and mental performance in the goal-directed behaviour. CNV: In the current study the appearance of a pointer of a symbolised clock at the 12 o'clock position represented the S1 stimulus, the beginning of the pointer movement represented the S2 stimulus (as soon as the pointer started to move, the subjects had to stop the pointer by pressing a mouse key). BP: To investigate the BP the subjects were asked to press a key with their right index finger 30 times at self-paced intervals (simple finger movements).
Power was measured using a power meter at the telephone connector. SAR measurements performed in 1996 on the basis of the CENELEC standard showed the peak values indicated. At the depth of about 14 mm, SAR amounted to about 25% of the energy at the skin surface.