Corresponding Author Information: Claudia Pignolo

Session Abstract: BACKGROUND AND PURPOSE: The Inventory of Problems-29 (IOP-29; Viglione, Giromini, & Landis, 2017) is a self-administered measure of symptom validity and credibility. Recently, a new forced-choice add-on implicit recognition task named the Inventory of Problems-Memory module (IOP-M) was introduced to be used in combination with it. Although available, empirical data strongly support the validity of the IOP-29, research using both the IOP-29 and IOP-M is still scarce. The current study aimed at filling this gap in the literature by administering the IOP-29 and IOP-M to a relatively large, Italian, community sample. METHODS AND MATERIALS: Two studies were conducted, one focused on feigning of depression, and one focused on feigning of PTSD symptoms. In the depression group (n = 239), participants were divided into honest and feigner conditions based on their scores on the Center for Epidemiologic Studies Depression Scale (CES-D): those who scored 20 or higher on the CES-D were asked to take the IOP-29 and IOP-M honestly, whereas those who scored lower than 20 on it were asked to feign depression. Similarly, in the PTSD group (n = 250), participants who scored 33 or higher on the Impact of Event Scale - Revised (IES-R) were asked to take the IOP-29 and IOP-M honestly, whereas participants who scored lower than 33 were asked to feign PTSD. All experimental simulators were given a vignette to facilitate feigning and were warned that if they presented their symptoms too dramatically, their performance would not be believable. ANALYSES: We inspected the effect sizes of the differences between the scores of honest responders and simulators and examined AUC and classification accuracy of both the IOP-29 and IOP-M. RESULTS: The IOP-29 showed very large effect sizes (i.e., d > 3.3) in both groups, whereas the IOP-M showed moderate (d = 1.14) to large (d = 1.41) effect sizes. When the recommended cut score of FDS ‚â• .50 was used, the IOP-29 produced Se = .88, Sp = .97, and OCC = .94 in the PTSD group, and Se = .88, Sp = .96, and OCC = .93 in the depression group. As expected, including the IOP-M yielded increased sensitivity in both groups, reaching .91 and .92 values respectively. CONCLUSIONS: Overall, the results indicate that using both the IOP-29 and IOP-M provides increased classification accuracy rates compared to using the IOP-29 alone.

Presenters:

Claudia Pignolo | Department of Psychology, University of Turin, Turin, Italy

Luciano Giromini, PhD | Department of Psychology, University of Turin, Turin, Italy

Alessandro Zennaro | Department of Psychology, University of Turin, Turin, Italy

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