What do potential research subjects take for granted when they consent to participate?

While intended to safeguard values of autonomy and respect, informed consent documents are often criticized as opaque, legalistic exercises, more concerned to provide institutional cover than communicate. Efforts to counter this tendency advocate a consent process conceptualized as an engaged dialogue responsive to subjects' information needs. Ironically, “consent as conversation” advocates have not gathered data on these needs, and make little use of empirical descriptions of how conversations work.

Using a conversational presupposition framework, we investigated whether, when considering research participation, people request the information IRBs typically require for informed consent. Of 51 participants approached in a public area and asked to be in a study, about half (51%) asked about the scientific purpose; 37% asked about time required, and 23% asked about the investigator. One person asked about data privacy. Nobody asked about other consent elements: voluntariness, freedom to discontinue, data maintenance, study risks/benefits, or IRB approval. Follow up questions found that many did not ask because they assumed they knew the answer, or did not anticipate the answer would matter to them.

Findings are consistent with conversation theory's claim that listeners do not normally believe speakers should tell them information they already assume to be true. There may be tensions between conversational disapproval of mentioning taken-for-granted information and the IRB requirement that each element of consent be explicitly spelled out for the participant to be considered informed. Implications of empirical studies of the consent process are discussed.