A Natural Experiment Design Testing the Effectiveness of the IOP-29 and IOP-M in Assessing the Credibility of Reported PTSD Symptoms in Belgium

ABSTRACT

Sometimes forensic psychologists are asked to determine whether the symptoms of PTSD presented by the plaintiff are genuine or feigned. To this end, they may use both symptom validity tests (SVTs) and performance validity tests (PVTs), but SVTs are used far more frequently in these assessments. Thus, we conducted a natural experiment and administered an SVT (i.e., the IOP-29) and a PVT (i.e., the IOP-M) to 76 individuals instructed to feign PTSD and to 34 controls who self-reported exposure to a devastating flood several months earlier. The results confirm the utility of both measures in detecting feigned PTSD.

KEYWORDS:

• Malingering
• PTSD
• IOP-29
• IOP-M
• assessment

Disclosure statement

The first, second, and fourth authors declare that they have no conflict of interest to disclose. In contrast, the third (Donald Viglione) and fifth (Luciano Giromini) authors report that they are members of the LLC that owns the rights to the IOP-29 and IOP-M.

Data availability statement

Authors are willing to share their data set upon reasonable request. To obtain the data set associated with this article, please contact the corresponding author at [email protected]

Ethical approval

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. The Institutional Review Board of the University of Turin has approved the project on Feb 28, 2022 (Prot. n. 0169445).

Informed consent

Informed consent was obtained from all individual participants included in the study.