What do I need to do if I don't want my participants to know the true purpose of my study (i.e., I want to use deception)?

Does my research meet the TCPS guidelines for using deception?

According to TCPS2(2022) Article 3.7A, The REB may approve research that involves an alteration to the requirements for consent set out in TCPS2(2022) Article 3 [3.1 to 3.5] if the REB is satisfied, and documents, that all of the following apply:

  1. the research involves no more than minimal risk to the participants;
  2. the alteration to consent requirements is unlikely to adversely affect the welfare of participants;
  3. it is impossible or impracticable to carry out the research and to address the research question properly, given the research design, if the prior consent of participants is required;
  4. in the case of a proposed alteration, the precise nature and extent of any proposed alteration is defined; and
  5. the plan to provide a debriefing (if any) which may also offer participants the possibility of refusing consent and/or withdrawing data and/or human biological materials, shall be in accordance with TCPS2(2022) Article 3.7B.

Particular attention must be paid to projects involving deception. Improper handling of such projects can lead to a loss of trust on the part of the participant community. The principle of free and informed consent is violated when deception is used, and the researcher must give the participant the opportunity to engage in free and informed consent after the project is complete in order to restore this trust. The manner in which this ‘second’ free and informed consent is obtained will vary depending on the nature of the potential harms or risks involved in the research. The following describes a proportionate approach to obtaining ‘second’ consent in cases of deception.

  1. Any protocol which is deemed to be higher than minimal risk will be reviewed at a meeting of the full board. If the protocol also involves deception, immediate debriefing will likely be required.
  2. Omission and Commission
    • In cases of deception by commission, researchers must actually tell a participant something which is untrue. This would be considered a more serious form of deception, and immediate, signed, written debriefing would usually be required.
    • In cases of deception by omission, researchers simply fail to tell the participant everything they need to know in order to make an informed decision about consent. This would be considered a less serious form of deception, and while immediate debriefing would be encouraged, it would not necessarily be required if the researcher could give sound reasons which it should not be necessary.
    • There are cases of deception by omission in which the information which the researcher has not told the participant would not in any way affect the participant’s decision to take part in the research. An example might be putting different posters in the room where participants are filling out surveys. In this case, an oral debriefing would be sufficient, informing participants of the deception, the reason for deception, and that if they wish their data to be withdrawn, they could contact the researcher.
  3. Psychological Distress

In cases where participants are recruited largely from the student population, the proposal is to put the participant temporarily under increased psychological distress, researchers should refrain from running experiments during periods when students are typically experiencing high levels of stress (such as exam prep periods).


A. For cases of simple deception (where it is unlikely to affect the consent decision)

  • Would receive delegated review if lower than minimal risk.
  • Debriefing can be proportionate to the sensitivity of the issue.
  • Can be done orally and with written handout sheet – signature not needed.
  • Simple, straightforward candid disclosure – for example “You were not told the true purpose of the project…” or “You were deceived in the initial consent form because…”
  • Be alert and sensitive to participant’s needs, feelings, reactions, and concerns.
  • Provide an opportunity for the participant to indicate their consent or refusal at the conclusion of the project – this can be done orally.
  • The researcher can argue for the delay of the debriefing to the end of the project.
  • The participant can be provided with the researchers’ contact information and invited to contact the researcher if they do not wish their data to be used.
  • Provide contact information for the REB.

B. For cases of more serious deception (where it might affect the consent decision) or cases of commission.

  • Will be reviewed by the full REB.
  • A full explanation of why participants were temporarily led to believe that the research, or some aspect of it, had a different purpose, or
  • A full explanation of why participants received less than full disclosure.
  • Why consent was not obtained prior to collection of data and/or human biological materials
  • Give details about the importance of the research.
  • State why partial disclosure or deception was necessary.
  • Address any concerns raised by the participant.
  • Remove any misconceptions that may have arisen by explaining why deception was necessary in order to ensure the validity of the research.
  • Re-establish trust that might have been lost.
  • Be alert and sensitive to participant’s needs, feelings, reactions, and concerns.
  • Provide an opportunity for the participant to indicate their consent or refusal at the conclusion of the project.
  • The REB is less likely to consent to the delay of the debriefing to the end of the project.
  • Give participants the opportunity to have their data removed from the project.
  • Provide contact information for the REB.

C. When to debrief

  • Immediately after completion of the interaction with a participant, where feasible.
  • If immediate debrief is difficult, the REB may approve deferring it to the end of the project, depending on the degree of seriousness of the deception.
  • For participants who lack the decision-making ability to provide consent, it may be necessary to debrief parents, guardians, or authorized third parties as well as the participant.
  • Community debrief may be necessary.

Wording for Debriefing Forms

Specific wording will be dependent on the research and the deception used, but should address the points raised above under Debriefing according to the level of deception seriousness.

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