Number 352 (Story #2), December 22, 1997 by Phillip F. Schewe and Ben Stein THE PHYSICS OF POSTURE. In order for a person to stand up straight a number of sophisticated sensory systems must work together: the vestibular (inner ear), the proprioceptive (sense of touch), and the visual. In order to understand this process better, scientists at Boston University (contact Carson Chow, 617-353-1491, invite@lamisun1.epfl.ch until Jan 1; ccc@bu.edu thereafter) have put subjects on a special force-sensitive platform which records the minutiae of their swaying motions. Subjecting this digitized information to a statistical analysis, the Boston researchers conclude that the way in which the posture control mechanism strives to maintain an upright posture is the same whether the subject is merely swaying in a random fashion standing at ease or is being perturbed by a slight external push. This issue had been of great interest to those who treat patients with apparent balance problems. (Lauk et al., upcoming article in Physical Review Letters.)