Volunteer and nonvolunteer characteristics in an outpatient population.

Data pertaining to the psychological characteristics of volunteers and nonvolunteers among a group of psychiatric outpatients were reported. Nonvolunteer patients included a significantly higher number of schizophrenics and borderline schizophrenics while volunteer patients tended to be more "ego involved" in psychotherapy. No statistically significant differences were found on occupational status, income, or education. MMPI scale score differences, while not significant, were in opposite directions from those usually observed in normal groups.