Digit Memory Test Research Articles

Base Rate of Hiscock Digit Memory Test Failure in HIV-Associated Neurocognitive Disorders

There is an emergent need for base rate data on symptom validity tests (SVTs) in clinical populations that are likely to seek disability benefits. The inclusion of HIV under the Americans with Disabilities Act has prompted many persons with HIV-1 infection to apply for disability, which raises the concern that a subset of these individuals might feign cognitive deficits to obtain benefits. This brief report provides base rate data on one SVT, the Hiscock Digit Memory Test (HDMT), in a sample of 82 non-compensation-seeking, neuropsychologically impaired participants who met diagnostic criteria for an HIV-associated neurocognitive disorder. Approximately 98% of individuals with HIV-associated neurocognitive disorders performed above an established HDMT cutoff for suboptimal effort (i.e., HDMT = 90% accuracy), whilst 95% of the sample obtained perfect scores. Clinicians can therefore be confident that, in the absence of severe dementia or amnesia, HDMT scores below standard cutoffs are unlikely to be solely attributable to HIV-associated cognitive impairment.

Cross-validation of indicators of malingering: a comparison of nine neuropsychological tests, four tests of malingering, and behavioral observations

Few studies to date have cross-validated indicators of malingering that have been suggested on various neuropsychological tests. This study presents data cross-validating several indicators of malingering on neuropsychological tests, as well as on tests of malingering and via behavioral observations. It incorporates methodological recommendations by Rogers [Researching dissimulation. In: R. Rogers (Ed.), Clinical assessment of malingering and deception (pp. 309–327). New York: Guilford Press.] resulting in an ecologically valid design utilizing college students with a history of mild head injury as analog malingerers. Results indicated that the Letter Memory Test (LMT) and the Digit Memory Test (DMT) attained the highest hit rates for the detection of malingering, while the sensitivity of many other measures declined on cross-validation.

Cross-validation of indicators of malingering: a comparison of nine neuropsychological tests, four tests of malingering, and behavioral observations

Few studies to date have cross-validated indicators of malingering that have been suggested on various neuropsychological tests. This study presents data cross-validating several indicators of malingering on neuropsychological tests, as well as on tests of malingering and via behavioral observations. It incorporates methodological recommendations by Rogers [Researching dissimulation. In: R. Rogers (Ed.), Clinical assessment of malingering and deception (pp. 309-327). New York: Guilford Press.] resulting in an ecologically valid design utilizing college students with a history of mild head injury as analog malingerers. Results indicated that the Letter Memory Test (LMT) and the Digit Memory Test (DMT) attained the highest hit rates for the detection of malingering, while the sensitivity of many other measures declined on cross-validation.

Bispectral Index Monitoring during Sedation with Sevoflurane, Midazolam, and Propofol

Bispectral Index (BIS) has been used to measure sedation depth. Ideally, to guide anesthetic management, range of BIS scores at different sedation levels should not overlap, and BIS should be independent of drug used. This study assessed ability of BIS to predict sedation depth between sevoflurane, propofol, and midazolam. Quality of recovery was also compared. Patients undergoing surgery with local or regional anesthesia and sedation were randomized to sevoflurane (n = 23), midazolam (n = 21), or propofol (n = 22). Sedation was titrated to Observers's Assessment of Alertness-Sedation score of 3 (responds slowly to voice). BIS and Observers's Assessment of Alertness-Sedation were measured every 5 min. BIS prediction probability (PK) was compared between drugs. Recovery was assessed by BIS and Digit Symbol Substitution and memory tests. Bispectral Index of responders to voice was significantly different from nonresponders (86 +/- 10 vs. 74 +/- 14, mean +/- SD; P < 0.001) However, wide variability and overlap in BIS were observed (25th-75th percentile, responders vs. non-responders: 79-96 vs. 65-83). BIS of responders was different for sevoflurane versus propofol and midazolam. BIS was a better predictor of propofol sedation than sevoflurane or midazolam (PK = 0.87 +/- 0.11, 0.76 +/- 0.01, and 0.69 +/- 0.02, respectively; P < 0.05). At 10 min after the procedure, 76, 48, and 24% of sevoflurane, propofol, midazolam patients, respectively, returned to baseline Digit Symbol Substitution scores (P < 0.05). Excitement-disinhibition occurred in 70, 36, and 5% of sevoflurane, propofol, and midazolam patients, respectively (P < 0.05). Individual BIS scores demonstrate significant variability, making it difficult to predict sedation depth. The relation between BIS and sedation depth may not be independent of anesthetic agent. Quality of recovery was similar between drugs, but excitement occurred frequently with sevoflurane.

Combining representations in working memory: A brief report

A task combining both digit and Corsi memory tests was administered to a group of 75 children. The task is shown to share variance with standardized reading and maths attainments, even after partialling out performance on component tasks separately assessed. The emergent task property may reflect coordination skills, although several different refinements can be made to this general conclusion.

Detection of Inadequate Effort on Neuropsychological Testing A Meta-Analytic Review of Selected Procedures

Thirty-two studies of commonly researched neuropsychological malingering tests were meta-analytically reviewed to evaluate their effectiveness in discriminating between honest responders and dissimulators. Overall, studies using the Digit Memory Test (DMT), Portland Digit Recognition Test (PDRT), 15-Item Test, 21-Item Test, and the Dot Counting Test had average effect sizes indicating that dissimulators obtain scores that are approximately 1.1 standard deviations below those of honest responders. The DMT separated the means of groups of honest and dissimulating responders by approximately 2 standard deviations, whereas the 21-Item Test and the PDRT separated the groups by nearly 1.5 and 1.25 standard deviations, respectively. The 15-Item Test and the Dot Counting Test were less effective, separating group means by approximately 3/4 of a standard deviation. Although the DMT, PDRT, 15-, and 21-Item Tests all demonstrated very high specificity rates, at the level of individual classification, the DMT had the highest sensitivity and overall hit-rate parameters. The PDRT and 15-Item Test demonstrated moderate sensitivity, whereas the 21-Item Test demonstrated poor sensitivity. The less than perfect sensitivities of all the measures included in this review argue against their use in isolation as malingering screening devices.

Development and initial validation of a new procedure for evaluating adequacy of effort given during neuropsychological testing: The letter memory test.

The authors report on results from a new procedure for evaluating adequacy of effort given during neuropsychological testing. The letter memory test (LMT) is a computer-administered, 45-item, forced-choice recognition task that uses consonant letters as stimuli and manipulates face difficulty level along 2 dimensions: number of letters to be remembered and number of choices amongst which the target stimulus must be identified. In 3 studies that included either analogue or known groups designs, the LMT discriminated poorly motivated from well-motivated groups at a moderately high level of accuracy, which was comparable to that of the Digit Memory Test and superior to that of the 21-Item Test. The internal consistency reliability of the LMT was also high.

Alpha rhythm parameters and short-term memory span

The study examined a statement from the neurophysiological model of A.N. Lebedev as to whether short-term memory span is related to a ratio of the alpha-rhythm frequency and parameters of step-type behaviour of wave processes in the EEG alpha range. Forty young healthy subjects performed a digit memory test. EEG signals were recorded from the occipital area during a resting period with eyes closed. As one of the parameters of step-type behaviour of alpha oscillations a mean value of the difference between periods of neighbouring peaks in the alpha spectra was calculated. A second parameter — the duration of alpha spindles, considered to be a superposition of alpha oscillations — was also measured. It was shown that the ratio of the alpha-rhythm frequency to parameters of the step-type behaviour of alpha oscillations positively correlated with memory performance. © 1997 Elsevier Science B.V.

Suspected Malingering and the Digit Memory Test: A Replication and Extension

This study replicated a previous finding that suspected malingerers often perform at a level worse than patients with unequivocal brain dysfunction on the Digit Memory Test (DMT). In addition, it was demonstrated that patients suffering from aphasia as well as temporal and “frontal lobe” damage perform at a level higher than suspected malingerers. DMT performance of patients with true dementia, however, may be difficult to distinguish from suspected malingerers. If an individual is not demented (as judged by such tests as the BNI Screen for Higher Cerebral Functions) and performs at a level less than 95% across three trials of the DMT, the question of noncooperation with testing procedures or “malingering” should be considered. © 1997 National Academy of Neuropsychology. Published by Elsevier Science Ltd

Suspected Malingering and the Digit Memory Test: A Replication and Extension

This study replicated a previous finding that suspected malingerers often perform at a level worse than patients with unequivocal brain dysfunction on the Digit Memory Test (DMT). In addition, it was demonstrated that patients suffering from aphasia as well as temporal and “frontal lobe” damage perform at a level higher than suspected malingerers. DMT performance of patients with true dementia, however, may be difficult to distinguish from suspected malingerers. If an individual is not demented (as judged by such tests as the BNI Screen for Higher Cerebral Functions) and performs at a level less than 95% across three trials of the DMT, the question of noncooperation with testing procedures or “malingering” should be considered. © 1997 National Academy of Neuropsychology. Published by Elsevier Science Ltd

Digit memory test: Unequivocal cerebral dysfunction and suspected malingering

The Digit Memory Test (DMT) (Hiscock & Hiscock, 1989), a forced-choice test for detecting malingering, was administered to 27 patients with unequivocal cerebral dysfunction, 5 patients with postconcussional syndrome, 6 suspected malingerers and 10 normal controls. Results indicate that, even in patients with severe, but static cerebral dysfunction and unequivocal memory disorder, DMT performance is between 95% to 100% correct. By contrast, the 6 patients in whom malingering was seriously considered performed at a level much below the other three groups (74% correct) but not significantly below chance. The DMT may be helpful in evaluating patients suspected of malingering even when they do not score significantly below chance.

WIC AND SOMATIC AND PSYCHOLOGICAL DEVELOPMENT OF PRE SCHOOL CHILDREN: THE NATIONAL WIC EVALUATION

We related age of onset of benefits from the Special Supplemental Food Program for Women, Infants and Children (WIC) to height, weight, Quetelet's index (wt/length2), head circumference, mid-arm circumference and triceps and subscapular skinfold thickness among 2142 representative poor children under five from 59 areas nationwide and behavior and cognition among 486 four and five year olds. We used Schaeffer's Infant Behavior Inventory, the Peabody Picture Vocabulary test and the forward and backward digit memory tests from the McCarthy Scale of Infant Development. We controlled for age and sex, and then for a wide range of additional social, demographic and somatic covariates.Highly significant improvements in children's diets by WIC were not reflected by advantages in linear growth. WIC participants were significantly shorter than controls (0.8 cm). Early WIC recruits had no parallel decrease in head circumference. We conclude that a) the WIC program is targeted to appropriate (short and deprived) children; b) identifying adequate controls for WIC recipients may now be impossible, with the wide diffusion of the program; c) it is unlikely that WIC benefits had any effect on linear growth; d) early WIC benefits had some beneficial effect on later head, and presumably, brain growth. Prenatal WIC recipients had significantly better performance on the PPVT, and later recruits had significantly better (backward) digit memory. There were no significant differences in child behavior. The implications of these observations will be discussed.