ABSTRACT
The various activities of the body involve chemical, mechanical, and electrical processes. Measures of chemical reactions are best left to the biochemist and physiologist. In psychophysiological research, numerous measures of mechanical reactions have been used. Techniques to record covert speech activity during thought involved such devices as inflated balloons and flattened wine glasses placed on or about the tongue; such “sensors” then had mechanical connections to recording systems of tambours and kymographs. In collaboration with Bell Telephone Laboratories, Jacobson eventually developed the integrating neurovoltmeter, which he used successfully both in his scientific and clinical work. Contrary to opinion of the time, Jacobson showed that muscle tonus could be reduced to a level of zero microvolts by the use of progressive relaxation technics.
