In conducting research involving human participants, ethics dictate that informed consent must be obtained prior to their participation. Informed consent means that “participants have adequate information regarding the research; are capable of comprehending the information; and have the power of free choice, enabling them to consent voluntarily to participate in the research or decline participation”. From this definition, the elements of informed consent are: adequate information, the capacity to understand this information and free choice. The key element is sufficient understanding because it makes the given information useful in making a free choice between assent and dissent.
In order to ensure that a participant sufficiently understands the information provided for him or her, several strategies can be used. After discussing pertinent information about the study, the researcher can ask the participant to state the topic of the study and enumerate the procedures it entails in his or her own words. The participant’s ability to accurately answer these questions reflects comprehension that is enough to provide informed consent. However, this is applicable only to individuals with sound mind and who are within the developmental stage where cognitive understanding of the given information is expected.
The use of a tool is also helpful in establishing understanding or decisional capacity even in participants with psychiatric conditions. In a review of the different tools used to measure decisional capacity, the MacArthur Competence Assessment Tools for Clinical Research and Treatment enjoys the most research evidence. This instrument quantifies participant understanding, reasoning, appreciation and expression of choice which are considered the elements of decisional capacity. High scores indicate sufficient understanding and low scores indicate a questionable informed consent.