Using the inventory of problems – 29 (IOP-29) with the Test of Memory Malingering (TOMM) in symptom validity assessment: A study with a Portuguese sample of experimental feigners

Abstract

This study tested whether combining the Inventory of Problems – 29 (IOP-29) with the Test of Memory Malingering (TOMM) would increase sensitivity in the detection of experimentally feigned mental health problems, compared to using either test alone. Additionally, it also evaluated (a) the effects of administration order of these two tests and (b) the cultural and linguistic applicability of these tests to a European Portuguese population. The IOP-29 and TOMM were administered to a community sample of 100 nonclinical, adult volunteers from Portugal, with the instruction to feign mental health problems. Half were instructed to feign mild traumatic brain injury (mTBI) symptoms, half were instructed to feign major depression. Administration order had no effects on the tests’ scores, and both measures produced excellent sensitivity values, ranging from .82 to .98 for the TOMM, and from .88 to 1.00 for the IOP-29, when using standard a priori cutoff scores. More importantly, combining the results of TOMM with those of IOP-29 notably increased sensitivity compared to using either test alone. This study thus supports the use of the IOP-29 together with the TOMM in multimethod symptom validity assessments and provides initial evidence that both tests can be used also in Portugal.