MMPI-2 SCALE F(þ) and Symptom Feigning: Scale Refinement

Abstract

The F(l=thorn) scale of the MMPI-2 is widely used to help identify exaggeration of psychological problems in psychiatric, forensic, and neuropsychological settings. The scale was constructed by selecting all MMPI-2 items (N = 27) that were endorsed by less than 20% of a sample of VA psychiatric inpatients and 20% of the normative sample used in restandardizing the MMPI-2. Although þ is used to measure symptom exaggeration and malingering, 4 of its 27 items load on the Lie (L) scale, which is known to be a measure of defensiveness and symptom underreporting. These four items, which express a denial of occasional anger, irritability, and procrastination, could conceivably measure an uncommon expression of defensiveness. This study used 150 neuropsychological referrals to test the hypotheses that (a) the four L scale items measure defensiveness, not exaggeration, and (b) the elimination of these items improves the utility of þ in assessing symptom exaggeration. The results indicate that the four L scale items are associated with defensiveness, not with symptom exaggeration. One third of the patients had an average T-score artifact of 9.5 points on þ as a result of endorsing these L scale items, with a range of OT to 21 T. Using the K scale as a criterion for level of problem disclosure, a shortened version of þ (omitting the four L scale items) was superior to þ as a measure of symptom exaggeration (r= -.46 vs. -.36, r² = 21% vs. 13% of the variance). The implications for clinical practice are discussed.