Sexuality research is often regarded as more intrusive than other types of research, contributing to sample self-selection biases. Researchers have consistently found that volunteers and non-volunteers for sexuality studies differ on a number of sexuality-related variables. Despite a large number of studies examining volunteer biases, relatively few have examined the effects of gender and exclusivity of sexual attraction on willingness to volunteer. Given that comparisons on the basis of gender and/or sexual attraction are frequently made in sexuality studies, understanding how these factors may contribute to volunteer bias is particularly important. In the current study, we investigated the impact of gender and sexual attraction, as well as individual difference variables, on hypothetical willingness to volunteer for a variety of sexuality studies, including new measurement technologies not previously investigated. Greater proportions of men and individuals with any degree of same-gender attraction reported that they were willing to volunteer for eye tracking and psychophysiology studies, whereas there were no significant effects of gender or sexual attraction on willingness to volunteer for sexuality surveys. The proportions of volunteers willing to participate were inversely related to study invasiveness. Greater sexual experience and more positive sexual attitudes were significant predictors of willingness to volunteer, whereas gender, sexual attraction, and other sexuality characteristics were not significant predictors. Implications of volunteer bias for research findings are discussed. Strategies to minimize volunteer bias and to examine whether or not recruited samples differ from the population are provided.
Keywords: Gender; Individual differences; Sex research; Sexual attraction; Volunteer bias.