Health Locus of Control and Symptom Validity Testing in a Military Context

Objective The base rate of symptom validity test (SVT) failure in the military has been the subject of recent investigation. Secondary gain is a potential factor in this population; however, frank malingering may not account for all cases of SVT failure. As a result, other psychological and social factors potentially associated with validity test failure have been suggested and include nocebo effect, diagnosis threat, and perceived injustice. Locus of Control (LOC) has been associated with a range of medical/psychological conditions/outcomes and this study examined the relationship between LOC and SVT performance. Method A retrospective review of adult patients administered the Multi-dimensional Health Locus of Control Scale (MHLCS) and the MMPI-2-RF (n = 53) or the PAI (n = 143) in the context of neuropsychological assessments in a military treatment facility was conducted. Results MHLCS Internal and Powerful Others subscales had very limited associations with the evaluated SVTs. However, the MHLCS Chance subscale was significantly correlated with MMPI-2-RF Fp (r = .37, p < .05) and Fs (r = .29, p < .05) and PAI NIM scales (r = .26, p < .01). The MHLCS Chance subscale scores were significantly higher in those failing the PAI NIM (t = 3.0, p < .01) and MMPI-2-RF Fp (t = 2.5, p < .05) and FBS (t = 2.5, p < .05) scales, with moderate to large effect sizes (Cohen’s d ranging from 0.76 to 0.99). Conclusions The current data indicate limited relationships between MHLC internal and powerful others subscales and SVT performance. However, higher Chance subscale scores were associated with failed SVTs.

Performance and Symptom Validity

Position papers from the American Academy of Clinical Neuropsychology and the National Academy of Neuropsychology define assessment of symptom and performance validity, using well-validated assessment tools, as a critical component of a competent neuropsychological assessment. The ability to provide information to the court about whether defendants/plaintiffs are providing accurate information about their symptoms and abilities is a unique and valuable contribution that our field brings to the forensic table. This chapter addresses strategies to assist jurors and other triers of fact in their understanding of concepts of effort and exaggeration, through evaluation of noncredible symptom patterns and performance validity and symptom validity testing.

Symptom Validity Testing

Symptom validity testing (SVT), also known as forced-choice testing, is a means of assessing the validity of sensory and memory deficits, including tactile anesthesias, paresthesias, blindness, color blindness, tunnel vision, blurry vision, and deafness. The common feature among these symptoms is a claimed inability to perceive or remember a sensory signal. SVT comprises two elements: a specific ability is assessed by presenting a large number of items in a multiple-choice format, and then the examinee's performance is compared to the statistical likelihood of success based on chance alone. These tests usually present two alternatives; thus the probability of simply guessing the correct response (equivalent to having no ability at all) is 50%. Thus, scores significantly below chance performance indicate that the sensory cues must have been perceived, but the examinee chose not to report the correct answer—alternative explanations are not apparent. SVT also has the capacity to demonstrate that the examinee performed below the probabilities of chance. Scoring below a norm can be explained by fatigue, evaluation anxiety, inattention, or limited intelligence. Scoring below the probabilities of chance alone most likely indicates deliberate deceptions and is evidence of malingering because it provides strong evidence that the examinee received the sensory cues and denied the perception. Even so, malingering must be evaluated from the total clinical context.