Researchers should distinguish between the process of informed consent, the documentation of informed consent, and written documentation of informed consent.
Informed consent should endure throughout the interaction between investigators and participants, rather than only at the beginning. The initial agreement to participate can be documented in various ways. When appropriate, usually where risks of harm are substantial, individually signed forms are the "gold standard" of informed consent.
Informed consent as a conversation needs to be available throughout the research, as subjects may develop questions or concerns when they are well into the research experience. For example, a discussion of confidentiality may not be really understood until they are asked very personal questions in the research experience. Subjects should feel free to raise questions at any point in the research.