Keep people informed or leave them alone? A suggested tool for identifying research participants who rightly want only limited information.

People taking part in research vary in the extent to which they understand information concerning their participation. Since they may choose to limit the time and effort spent on such information, lack of understanding is not necessarily an ethical problem. Researchers who notice a lack of understanding are in the quandary of not knowing whether this is due to flaws in the information process or to participants' deliberate choices. We argue that the two explanations call for different responses.A tool for identifying those research participants who want limited information is presented. This consists of a restricted number of questions about trust in and appraisal of research, priority of time and privacy, and perception of a duty to participate. It is argued that an important group of participants who purposely lack understanding of the study can be identified with this tool. Some limitations to this approach are also discussed.