Case File 238 · Investigation Psychology

Omission vs Fabrication: What Is the Difference?

By Murder Book Editorial TeamPublished by Gungrounds, the studio making Murder BookPublished 3 October 2026Updated 3 October 2026

Omission and fabrication are two different ways of misleading. Omission means leaving true information out — concealing. Fabrication means putting false information in — asserting something untrue. Both can be used to deceive, but they are not the same act, and they carry different risks for the person doing them. Leaving something out requires no false statement, which is why many people find it easier and feel less guilt about it. Making something up adds a false claim that can later be contradicted by evidence. Crucially, you cannot tell which one a person is using, or whether they are using either, just by watching their behaviour: research shows cues to deception are weak, and a gap in a story can be forgetting or privacy rather than concealment.

Key takeaways

Omission leaves true information out (concealing); fabrication puts false information in (falsifying).
Psychologists treat these as two distinct techniques with often the same goal — to mislead.
Fabrication adds a checkable false claim; omission leaves a gap, which is harder to detect but also, to some, feels less like lying.
Research finds liars tend to be slightly less forthcoming and give fewer details on some measures, but these tendencies are weak and not diagnostic.
No behaviour reliably reveals whether someone is omitting, fabricating, or being fully honest.

What is the core difference?

The difference is the direction of the move. Omission removes true information from an account; fabrication adds false information to it.

Omission (concealment): everything said is true, but something important is left unsaid.
Fabrication (falsification): a claim is made that the speaker believes to be false.

A person describing an evening might omit that they left the house for an hour, or fabricate that they were home the whole time. Both could mislead a listener, but only the second involves stating a falsehood — and only the second can be directly contradicted by, say, a receipt or a camera. For the standalone treatment of leaving things out, see what is omission.

How do researchers frame the two?

Paul Ekman's well-known split captures it exactly. He describes two major forms of lying: concealment, where "the liar withholds some information without actually saying anything untrue", and falsification, where the liar "present[s] false information as if it were true". Ekman notes these are different techniques for the same objective, that the choice between them is often just a matter of which will work better, and that people tend to feel less guilt about concealing than about falsifying.

Steven McCornack's Information Manipulation Theory (1992) maps the two onto different conversational maxims from the philosopher Paul Grice. Omission is a manipulation of quantity — giving less information than the situation requires. Fabrication is a manipulation of quality — giving information the speaker believes to be untrue. The theory's broader lesson matters here: because people can mislead using entirely truthful statements (through omission and emphasis), a great deal of deception leaves no false claim to catch at all.

	Omission (concealment)	Fabrication (falsification)
The move	Leaves true information out	Adds information believed to be false
False statement made?	No	Yes
Grice maxim (IMT)	Quantity	Quality
Easier to detect?	Harder — nothing false is said	Potentially easier — a false claim can be contradicted
Reported guilt (Ekman)	Often felt less strongly	Often felt more strongly
Proves guilt from behaviour?	No	No

Does fabrication leave more traces than omission?

Sometimes, but not in a way you can rely on. A fabricated claim is a hostage to fortune: it can be checked against physical evidence, records or other witnesses, and if it is false it may be contradicted. An omission leaves no such claim, so there is nothing specific to disprove — only a gap that may or may not be noticed.

There is also a modest pattern in the research. The 2003 meta-analysis of deception cues by Bella DePaulo and colleagues found that, on some measures, liars were a little less forthcoming and included fewer details than truth-tellers. This has inspired interview approaches that focus on checkable detail — the idea that invented accounts may contain fewer details that can be independently verified. Those approaches are discussed in the verifiability approach and reality monitoring. But the effects are tendencies, not switches: plenty of honest accounts are thin, and plenty of fabricated ones are richly detailed. None of this lets you label a single statement as omission or fabrication from the outside.

Why does neither prove deception on its own?

Because the behaviour around both is weak and ambiguous. The 2006 meta-analysis by Charles Bond and Bella DePaulo, covering more than 24,000 judges, found people sort lies from truths about 54% of the time. A 2019 Annual Review of Psychology paper by Aldert Vrij, Maria Hartwig and Pär Anders Granhag concluded that behavioural cues to deceit are faint and that people are mediocre lie-catchers when they rely on them.

Two innocent explanations keep the picture honest:

Gaps are often memory, not concealment. People genuinely forget and edit, so a missing detail is not necessarily hidden on purpose.
Wrong details are often error, not fabrication. An inaccurate statement can be an honest mistake, a misremembering, or confusion under stress rather than a deliberate falsehood. Is inconsistent behaviour evidence of deception looks at how easily these are over-read.

So the responsible conclusion is the same for both: an omission or an apparent falsehood is a reason to ask more and to seek corroboration, never a verdict in itself.

How should an interviewer handle the distinction?

Practically, the two call for the same discipline. For a suspected omission, ask a direct, specific question and see whether the gap fills. For a suspected fabrication, identify the checkable claim and test it against independent evidence rather than against a hunch about demeanour. In both cases the account is weighed against facts, not against body language. This is why information-gathering interviews stress eliciting detail and corroboration over watching for "tells".

How do omission and fabrication appear in Murder Book?

Murder Book: The Art of Interrogation is an upcoming narrative interrogation game from Gungrounds, an independent studio in Zagreb, Croatia. Its press kit names both sides of this distinction: Fabrication and Narrative Gaps sit among the behaviours players examine, alongside Avoidance and Emotional Leakage. A development evidence board even shows statements such as "I NEVER met her!" linked to a fabricated description — an in-game example of a false claim that can be tested against other evidence.

The research on this page is why the game treats both as starting points rather than proof. A gap in a story might be concealment or simple forgetting; a wrong detail might be a lie or an honest error. The work is to ask again and to check the account against what the evidence can confirm. Cases are built for focused 5–10-minute sessions, and Murder Book is in development for PC (Steam) and mobile, with release currently planned for the end of Q2 2027. For a wider view of the behaviours players read, see behavioral leakage explained.