Concealment" is involved when the researcher intentionally does not reveal initially to the participant all details of the protocol (not the whole truth). "Deception" is involved when participants intentionally are told something untrue (not the truth). Many professional organizations, such as the American Psychological Association, consider deception undesirable except in the rarest of cases. Strong justification must be provided for procedures calling for either concealment or deception, and participants must be fully informed at the conclusion of the activities, preferably with an opportunity to withdraw their data if they are bothered by the concealment or deception. APA Code of Ethics
6.15 Deception in Research
(a) Psychologists do not conduct a study involving deception unless they have determined that use of deceptive techniques is justified by the study's prospective scientific, educational, or applied value and that equally effective alternative procedures that do not use deception are not feasible. (b) Psychologists never deceive research participants about significant aspects that would affect their willingness to participate, such as physical risks, discomfort, or unpleasant emotional experiences. (c) Any other deception that is an integral feature of the design and conduct of an experiment must be explained to participants as early as is feasible, preferably at the conclusion of their participation, but no later than at the conclusion of the research. APA Code of Ethics Human Subject Research at Purdue
Purdue's Committee on the Use of Human Research Subjects has carefully reviewed this issue. At its meeting of May 28, 2002, the Committee found that voluntary informed consent cannot truly occur if the participant is not told that they will be deceived. It is, therefore, the policy of the Committee to allow deception to be used in human subject studies only when the following conditions are met: 1. The participant...