TABLE 1.

Summary of positions presented and empirical questions to be addressed.

Position	General understanding from the literature	Empirical research questions
Masturbation and ejaculation
…and the historical perspective	Ejaculation and masturbation have a long history of superstition. Perspectives on masturbation have changed from representing a harmful and deviant behavior to being perceived as normal and even healthy. However, this general notion varies depending on group membership. Large differences exist between countries, becoming evident in so-called “culture-bound syndromes.” Differences in attitude also run along group membership holding different value systems, educational levels, or professions.	Which factors exert systematic and significant impact on societal attitudes toward masturbation and ejaculation frequency. Is there an effect of societal attitudes on attitudes toward masturbation and ejaculation on individual level? Can those effects be categorized or explained?
…and quality of sperm	Sperm quality is described along six parameters (WHO spermiogram). Abstinence as influential factor has repeatedly been described, however, without clear time specifications.	Does ejaculation frequency significantly impact quality of sperm? If ejaculation frequency impacts quality of sperm, which are the parameters mostly affected? Is the effect of ejaculation frequency different for ejaculation due to masturbation or sexual intercourse?
…and hormonal influences	Human male sexuality is influenced by a complex interplay of biomarkers, predominantly by testosterone. The focus of literature lies on the causal direction. Little is known on the effects of ejaculation and masturbation frequency on testosterone levels.	Are there potential associations between different biomarkers and frequency? How do ejaculation/masturbation frequency and testosterone levels affect each other in the long run? Does ejaculation/masturbation abstinence significantly affect testosterone levels?
… and brain function and structure	Limited temporal resolution of imaging techniques and other context factors hamper the precise study of processes directly involved in ejaculation and orgasm.	Which brain structures are activated during ejaculation? What effects does frequent ejaculation have on typically involved structures and their function? Does a thorough understanding of the ejaculation process aid in the understanding and treatment of sexual dysfunctions?
…and modifiable lifestyle variables	Mental and general health and well-being are subject to different behaviors subsumed under the term “modifiable lifestyle factors.” Masturbation and ejaculation frequency have not been listed, however, represent modifiable, individual, and presumably influential factors regarding well-being. Some studies argue that not the behavior itself but rather accompanying attitudes and potential discrepancies between attitudes and behavior might exert the influence on well-being.	Is there a relation between masturbation and ejaculation frequency and mental and general health/well-being? Is the potential relation between masturbation and ejaculation frequency and mental and general health/well-being mediated through personal beliefs? Is a potential discrepancy between personal beliefs and individual behavior more important than the actual belief itself?