Voluntariness of consent for research: an empirical and conceptual review.

This article explores the vulnerability of research subjects either to undue influence or to coercion. The authors present a brief review of the requirement for voluntariness in research, and what is known about research participation. They then examine characteristics of potential subjects, researchers, researcher actions, and the research setting that can influence the voluntariness of subject's decisions to participate. Throughout the paper, empirical work that relates to voluntariness is used to illustrate the conceptual material. Voluntariness is viewed as an issue of self-control. Threats to voluntariness can arise from vulnerabilities of potential subjects as well as from characteristics of the researcher, the researcher's acts, and the research setting. Moral concerns about potential influences may be assessed by the likelihood that they will control or dominate a potential subject's decision to participate in research. Policy responses may be appropriate where the probability of control is too high.