Explicit consent. Participants give consent by answering a specific question about their willingness to participate. This may be done in written (consent form) or oral form.
Passive consent. Participants are informed of the study, and are considered to agree to participate unless they specifically decline to be included in the study. This procedure is often used in schools that send forms to parents asking them to allow their students to participate in various studies or activities. Although it yields high participation rates, it should be limited to completely innocuous research (typically not involving minors). It is acceptable for participant observation (ethnographic) projects.
Some participants, although not legally competent, are able to make judgment about their participation themselves. This is the case for teenagers and some mentally impaired individuals, for instance. The assent formgives them an opportunity to express their agreement to participate in research in writing, beyond the consent given by a legal guardian or parent. Although the assent is not legally binding, and does not dispense a researcher from obtaining consent from a parent or legal guardian, it is advisable as sound ethical practice. It reinforces the voluntary nature of participation.
To be informed, consent must be given by persons who are competent to consent, have consented voluntarily, are fully informed about the research, and have comprehended what they have been told. Unless they are emancipated minors, individuals under 18 may never give consent. Also question the legal competence of people affected by mental illness, or institutionalized in the prison system. If a person is not legally competent to give consent, a parent or legal guardian has to give it. The participant may still give assent.
vaccine consent form
microdermabrasion consent form
video consent form