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Overview
Limited disclosure and deception are techniques in which some information about the research is withheld from participants, or participants are actively misled, because full disclosure would compromise the validity of the research. The National Statement addresses these approaches in Chapter 2.3. This article covers limited disclosure as a research technique: when it can be used, what has to be justified, and what follows once data collection ends. For the consent-mechanism perspective on the same provisions, see When consent can be modified.
Forms of limited disclosure
Limited disclosure sits on a spectrum. At the less interventionist end, a researcher may withhold the specific aims of an observational study to avoid priming participants, without actively misleading anyone. At the more interventionist end, a researcher may actively conceal the true purpose of the research or the identity of the researcher, which the National Statement treats as active concealment or planned deception (NS 2.3.2). A further category covers research that aims to expose illegal activity, where the adverse effects on those exposed must be justified by the value of the exposure (NS 2.3.3).
Approval requirements
All forms of limited disclosure must be approved by the review body before use; researchers cannot self-assess a departure from full disclosure as minor and proceed without approval. Where limited disclosure does not involve active concealment or planned deception, it may be approved by any appropriately authorised review body, including a lower risk review pathway where the research otherwise qualifies (NS 2.3.1). Where limited disclosure involves active concealment or explicit deception, or where the research aims to expose illegal activity, only an HREC can review and approve it; this cannot be delegated to a lower risk review process (NS 2.3.4).
Justification requirements
To obtain approval for any limited disclosure, researchers must demonstrate (NS 2.3.1):
- There is no suitable alternative involving fuller disclosure by which the research aims can be achieved.
- The potential benefits of the research justify both the limited disclosure to participants and any risk to public trust in research and researchers.
- The research involves no more than low risk to participants, and the limited disclosure is unlikely to affect participants adversely.
- The precise extent of the limited disclosure is defined in advance.
Where the limited disclosure involves active concealment or explicit deception, researchers must additionally demonstrate (NS 2.3.2):
- Participants will not be exposed to an increased risk of harm as a result of the concealment or deception.
- A full explanation of the real aims and methods, and of why the concealment or deception was necessary, will subsequently be made available to participants.
- There is no known or likely reason to think participants would not have consented had they been fully aware of what the research involved.
Debriefing
Where limited disclosure or deception is used, participants must, whenever possible and appropriate, be told after their participation has ended about the aims of the research and why the omission or alteration was necessary, and offered the opportunity to withdraw any data they have provided (NS 2.3.1(e)). Where active concealment or deception was used, the full explanation required by NS 2.3.2(b) should be given as part of this debriefing. Researchers should report the outcomes of debriefing, including any withdrawals, in their progress and final reports.
What reviewers look for
- Whether a fuller-disclosure alternative was truly unavailable, not merely inconvenient
- Whether the review pathway matches the form of limited disclosure: HREC-only where concealment, deception, or exposure of illegal activity is involved
- Whether the debriefing plan is concrete, timely, and includes the opportunity to withdraw data
Related resources
This page was last updated on 16 September 2026.
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This article makes reference to the National Statement on Ethical Conduct in Human Research 2025. It is intended as practical guidance and does not constitute legal advice.
AI Disclosure: Resources in this library were prepared using Large Language Models with input from Iris Ethics staff who guided the scope and design. Subsequent revisions and final versions were developed and approved by Iris Ethics staff.