Scheme of the experimental apparatus.

<p>Subjects rested their chin above a horizontal panel (W). Auditory targets were six miniature sound sources (S1), arranged semi circularly at 12 deg intervals. Visual targets were projected (P) via a mirror (M) onto W, just in front of the sound sources. Two sound boxes to the left (S2) and right (S3) of the subject informed about directional errors. Movement of the index finger (F) was registered by an electromagnetic 3D tracking system. The other arm rested on a table (T) underneath W.