High Specificity of the Word Memory Test and Medical Symptom Validity Test in Groups with Severe Verbal Memory Impairment
By definition, false positives occur when an otherwise very easy symptom validity test (SVT) or effort test is failed because of cognitive impairment and not because of poor effort. Therefore, the highest rate of false positives will be found in those groups with the most severe cognitive impairment. For that reason, it is important to study people with severe impairment when evaluating the specificity of SVTs. Some people with various types of dementia, notably those with Alzheimer’s disease, suffer from severe impairment of memory and other cognitive abilities. In this study, patients with possible or probable dementia were tested with the Word Memory Test (WMT; Green, 2003; Green & Astner, 1995) and the Medical Symptom Validity Test (MSVT; Green, 2004). While some dementia patients failed the easy subtests of these instruments and had severe verbal memory impairment, they showed distinctive profiles of scores that have been reported to be characteristic of people with severe impairment. Using profile analysis, the WMT and MSVT achieved a specificity of 98.4% or higher in the patients of the current study. This suggests that there will be extremely low false positive rates using the same methods in people with relatively minor impairment of the type found in, for example, mild traumatic brain injury or depression.
Embedded Effort Indicators on the California Verbal Learning Test – Second Edition (CVLT-II): An Attempted Cross-Validation
This study determined whether the logistic regression method that was recently developed by Wolfe and colleagues (2010) for the detection of invalid effort on the California Verbal Learning Test – Second Edition (CVLT-II) could be cross-validated in an independent sample of 100 consecutively referred patients with traumatic brain injury. Although the CVLT-II logistic regression formula demonstrated a statistically significant level of agreement with results from the Word Memory Test, it was associated with an unacceptably high proportion of false positives. The component variables of the logistic regression were sensitive to length of coma but did not covary with psychosocial complicating factors (e.g., unresolved prior psychiatric history) that were associated with a higher relative risk of failure of WMT validity criteria. It is concluded that the Wolfe et al. logistic regression should be used only with great caution in the context of clinical neuropsychological evaluations.
This article reviews current literature on vocal fatigue and considers its potential relationship to vocal hyperfunction. Vocal fatigue is defined by its symptoms. Specifically, the voice user perceives an increase in phonatory effort over time that may be accompanied by decreased phonatory function. Vocal fatigue can present as a pure condition, such that no specific aetiology is apparent, or as a component of other voice disorders. The underlying bases of vocal fatigue appear to include the neurophysiological and biomechanical effects of extended periods of phonation. It can also be a function of strategies used to adapt to extended periods of phonation, such as the use of excessive muscular tension and suboptimal vocal fold posturing. Studies that have attempted to identify observable responses that are reliably associated with vocal fatigue have met with limited success, but recent advances in research methodology are promising. This review addresses current approaches to the study of vocal fatigue, especially regarding subject selection, design variables, and measurement variables. Future studies should address the relationship between vocal fatigue and other voice disorders, differences in individual responses to vocal-loading tasks, and differential evaluation and management of the neuromuscular, biomechanical, and central processes involved in vocal fatigue.