Figure 1.

Schematic illustrations of the experimental conditions. (a) Control condition. The box was moved around horizontal and vertical axes. (b) Head/eyes condition. The experimenter turned the head together with eyes about 70° up, down, left, or right. (c) Eye condition. The experimenter oriented the eyes up, down, left, or right. (d) Trunk condition. The experimenter turned the trunk to the left or to the right. (e) Possible subject's response to the stimulus. Subject's response may fall into one of these four sectors. Each sector covers an area delimited by a 90° angle, 45° clockwise and counterclockwise with respect to the stimulus direction.