The view is presented that investigations on the electrophysiology of mental activities, although still in their infancy, have opened the way toward understanding and treatment of various common "psychoneuroses"[See Source Pdf for Illustration.] FIG. 6.—Graph of rectified action-potentials showing differential relaxation while reading, June 14, 1940. The electrodes are in the mid-line of the right quadriceps femoris muscle, respectively 2 and 4 inches above the patella. (The patient was discharged June 9, 1936.)according to physiological principles. It is suggested that certain more or less vague and figurative terms in current usage should be replaced by others more precise and descriptive but less theoretical in character. Among these is the term "psychoneurosis." Most of the variable conditions included under this caption can be diagnosed as "neuromuscular hypertension with pathological habit formation." Foundation for this revision lies not alone in the present studies but particularly in the vast literature concerning investigations on habit formation and on conditioned reflexes.Nervous and muscular states in man can now be measured accurately in the clinic, affording objective means of determining the progress of the patient or of testing the effects of any particular form of therapy. This is illustrated in the presentation of two cases of "psychoneurosis"—one characterized by phobias and the other by transient states of depression and irritability.Assuming that the symptoms during "psychoneurosis" essentially include neuromuscular tensions in various bodily localities, it would seem evident that the relaxation of these tensions would be the direct route to efficacious treatment, particularly if it could be made habitual. This procedure is followed in the cases cited.