One of the easiest methods of assessing understanding is called the "teach back" method. Once the consent presentation is completed the investigator might ask the potential subject to describe the purpose of the study, what the subject must do, the risks, the benefits, and the cost to the subject (if applicable) . Inconsistencies can be discovered and corrected at this time. If the subject appears to have adequate ability to related this information back to the investigator, then understanding has been demonstrated.In situations where the ability of the subject to understand the form is in question, for example, the subject is possibly educationally or mentally challenged, the investigator or member of the research team may wish to ask questions of the subject to ensure an understanding of the basic elements of the consent form. In performing an assessment of the subject's comprehension of the consent form, an investigator should request that the subject indicate the risks of participation, how the subject may withdraw, and what alternatives exist to participation in the research. The decision-making capacity of subjects with psychiatric disorders or cognitive deficits (such as dementia) should be evaluated by a practitioner with expertise in the area.
All efforts should be made to offer the potential subject or LAR sufficient time to consider the information contained in the consent form. The potential subject or LAR should be given the opportunity to take the consent form home and sign the form on a return visit or be left alone to consult about enrollment with family or friends. If the individual decides to participate, he/she is asked to sign the consent form. The person obtaining the subject's informed consent must also sign the form. The subject must be given a copy of the form the subject signed. The FDA (drug or device studies) explicitly requires that consent forms be dated as well as signed by the subject or the subject's legally authorized representative. The original consent is retained in the investigator's files.