Volunteer bias in the psychophysiological study of female sexuality

Volunteer bias occurs in all areas of human psychological research, limiting the ability of researchers to generalize results to the population at large. In this study, volunteers were compared to nonvolunteers for a study of female sexual response that utilized psychophysiological measurement of sexual aroused. All potential subjects completed questionnaire measures of sexual experience, current sexual activities, sex guilt, sexual arousability, and repression‐sensitization. Subjects then either volunteered or declined to participate after a full description of the research and recording instruments. Univariate analyses showed significant differences between those subjects who participated and those who did not on 27 of 37 variables studied. These variables were then subjected to a factor analysis and scores on the resulting nine factors were entered into a discriminant function analysis to predict volunteer status. Volunteers were found to have greater noncoital sexual experience, greater masturbatory experience, less sexual inhibition, and more experience with unusual sex. Implications of these findings for the study of sexuality are discussed.