Volunteer bias in human psychophysiological sexual arousal research: To whom do our research results apply?

The volunteer biases present in psychophysiological studies of sexual arous al were investigated in two geographically distinct sites. Four hundred eig hty-five male and female undergraduates at the University of North Dakota a nd Oklahoma State University completed a packet of questionnaires which inc luded demographics and personality- and sexuality-related measures. Partici pants were then given an opportunity to participate in a sexual arousal stu dy, for which 74 individuals volunteered. Significant differences were foun d between males and females on sexual guilt, and between volunteers and non volunteers on four out of five measures. In addition, analyses of the reaso ns nonvolunteers provided for not participating suggest that the types of m easurement and stimuli often influence what types of individuals volunteer for such research. These results have serious implications for the generali zability of such physiological arousal measures, and indicate a need for th e development of less intrusive measures of sexual arousal if results are t o be generalized beyond the samples studied.