The variation of hand tremor with force in healthy subjects

1. Total root‐mean‐square (r.m.s.) error over an effectively unrestricted band, and error power spectra from 0·256 to 12·5 c/s were measured for four subjects attempting to maintain fixed forces of 1‐6 Lb. (0·45‐2·72 kg) on a pressure joystick. The subject could see his errors as the deflexion of a cathode ray tube spot.