SVT Meets PVT: Development and Initial Validation of the Inventory of Problems – Memory (IOP-M)

A growing literature indicates that to evaluate the credibility of a clinical presentation it would be optimal to rely on multiple sources of information, and use both symptom validity tests (SVTs) and performance validity tests (PVTs) whenever possible. In this paper, we present the development and initial validation of a PVT module designed to be used in combination with a free-standing SVT. Named Inventory of Problems – Memory (IOP-M), this new PVT module is given to the examinee immediately after completing the Inventory of Problems – 29 (IOP-29). It consists of a 34-item, two-alternative, forced-choice, implicit recognition test. Results from 360 nonclinical volunteers – 192 instructed to respond honestly (honest controls) and 168 instructed to feign mental illness (experimental simulators) – suggest that the IOP-M has the potential to yield incremental validity over using the IOP-29 alone. In fact, a series of hierarchical logistic regressions using group as criterion variable (0 = honest control; 1 = experimental simulator) and the IOP-29 and IOP-M as predictors showed that the models including both measures significantly improved classification accuracy over those including the IOP-29 only, Δχ 2 ≥ 19.1, p