Background/Aim: Omission lies (lies whereby lie tellers deliberately leave out information they do not wish the target person to know) are frequently told, yet under investigated. Detecting such lies could be challenging for practitioners because all information a lie teller provides could be truthful. We examined the effect of (1) the size of the omission (leaving out a smaller or larger pieces of information) and (2) saliency of the reported information (whether the reported information is essential - about experiences that happened just before and just after the omission - or non-essential). Method: A total of 145 participants were sent on a mission in which they followed a target of interest. During the mission the target met two people at different locations. After completing the surveillance mission truth tellers reported the mission truthfully. Small-omission lie tellers omitted the second meeting that occurred and large-omission lie tellers omitted both meetings. We only analysed the parts of the mission that all lie tellers and truth tellers could truthfully report. The dependent variables were details, complications, common knowledge details and self-handicapping strategies. Results: Regardless the size of the omission, lie tellers reported more common knowledge details than truth tellers. This veracity effect occurred in both the essential and non-essential parts of information. Conclusions: Despite lie tellers being entire truthful, verbal differences occurred between their accounts and truth tellers’ accounts.
Vrij et al. (2026) studied this question.