Search

Introduction: Models from signal detection theory are commonly used to score neuropsychological test data, especially tests of recognition memory. Here we show that certain item response theory models can be formulated as signal detection theory models, thus linking two complementary but distinct methodologies. We then use the approach to evaluate the validity (construct representation) of commonly used research measures, demonstrate the impact of conditional error on neuropsychological outcomes, and evaluate measurement bias., Method: Signal detection-item response theory (SD-IRT) models were fitted to recognition memory data for words, faces, and objects. The sample consisted of U.S. Infantry Marines and Navy Corpsmen participating in the Marine Resiliency Study. Data comprised item responses to the Penn Face Memory Test (PFMT; N = 1,338), Penn Word Memory Test (PWMT; N = 1,331), and Visual Object Learning Test (VOLT; N = 1,249), and self-report of past head injury with loss of consciousness., Results: SD-IRT models adequately fitted recognition memory item data across all modalities. Error varied systematically with ability estimates, and distributions of residuals from the regression of memory discrimination onto self-report of past head injury were positively skewed towards regions of larger measurement error. Analyses of differential item functioning revealed little evidence of systematic bias by level of education., Conclusions: SD-IRT models benefit from the measurement rigor of item response theory-which permits the modeling of item difficulty and examinee ability-and from signal detection theory-which provides an interpretive framework encompassing the experimentally validated constructs of memory discrimination and response bias. We used this approach to validate the construct representation of commonly used research measures and to demonstrate how nonoptimized item parameters can lead to erroneous conclusions when interpreting neuropsychological test data. Future work might include the development of computerized adaptive tests and integration with mixture and random-effects models.

Objective: While some reports suggest that HIV+ individuals continue to display executive function (EF) impairment in the era of cART, findings have been contradictory and appear to differ based on the aspect of EF being measured. To improve the understanding of how discrete executive abilities may be differentially affected or spared in the context of HIV infection, we conducted a systematic review and meta-analysis to (a) determine whether and to what extent HIV+ adults experience deficits in EFs, and (b) understand how demographic and clinical characteristics may modify the associations between HIV infection and executive abilities., Method: Studies comparing HIV+ and HIV-uninfected groups on measures of working memory, set-shifting, inhibition, decision-making, and apathy between 2000 and 2017 were identified from three databases. Effect sizes (Cohen's d) were calculated using inverse variance weighted random effects models. Meta-regression was used to examine the moderating effect of demographic and clinical variables., Results: Thirty-seven studies (n = 3935 HIV+; n = 2483 HIV-uninfected) were included in the meta-analysis. Pooled effect sizes for deficits associated with HIV infection were small for domains of set-shifting (d = -0.34, 95% CI [-0.47, -0.20]) and inhibition (d = -0.31, 95% CI [-0.40, -0.21]), somewhat larger for measures of decision-making (d = -0.41, 95% CI [-0.53, -0.28]) and working memory (d = -0.42, 95% CI [-0.59, -0.29]), and largest for apathy (d = -0.87, 95% CI [-1.09, -0.66]). Meta-regression demonstrated that age, sex, education, current CD4 count, and substance dependence differentially moderated the effects of HIV infection on specific EFs. However, lower nadir CD4 count was the only variable associated with greater deficits in nearly all EF domains., Conclusions: Our results suggest that discrete domains of EF may be differentially affected by HIV infection and moderating demographic and clinical variables. These findings have implications for the development of targeted cognitive remediation strategies.

Background: The study explored the construct validity of a computational model of working memory (WM) by determining whether model parameters manifested double dissociations of lesion laterality with type of material studied. The data set modeled involved psychometrically matched verbal and figural WM tasks on which a double dissociation between test version and lesion laterality failed to emerge when total test scores were used as the laterality marker., Method: This re-analysis of a previously published study involved investigating the WM performance of 15 demographically matched controls with 15 adult patients with left-hemispheric (LH) lesions and 15 adult patients with right-hemispheric (RH) lesions. Each participant was given verbal and figural versions of a continuous paired associates test (CPAT). The two versions had previously been psychometrically matched in a larger sample of healthy individuals. A WM model composed of encoding, displacement, and episodic memory parameters was fit to each individual's performance profiles for both versions of the CPAT., Results: Replicating the previous results for raw scores, rank transformed values of total score performance failed to reveal a double dissociation. Nonetheless an absolute double dissociation was observed for the model's displacement parameter: RH patients demonstrated deficits on the figural but not verbal WM displacement parameter, whereas LH patients demonstrated deficits on the verbal but not figural WM displacement parameter. Additionally, both LH and RH patients were impaired on the figural encode parameter, perhaps explaining the absence of a double dissociation in total score performance., Conclusions: By combining different patterns of profile and level data into theoretically motivated model parameters, computational models of neurocognition can enhance the construct validity of interpretations of neuropsychological performance.

Introduction: We used cognitive and psychometric modeling techniques to evaluate the construct validity and measurement precision of latent cognitive abilities measured by a test of concept identification learning: the Penn Conditional Exclusion Test (PCET)., Method: Item response theory parameters were embedded within classic associative- and hypothesis-based Markov learning models and were fitted to 35,553 Army soldiers' PCET data from the Army Study to Assess Risk and Resilience in Servicemembers (Army STARRS)., Results: Data were consistent with a hypothesis-testing model with multiple latent abilities-abstraction and set shifting. Latent abstraction ability was positively correlated with number of concepts learned, and latent set-shifting ability was negatively correlated with number of perseverative errors, supporting the construct validity of the two parameters. Abstraction was most precisely assessed for participants with abilities ranging from 1.5 standard deviations below the mean to the mean itself. Measurement of set shifting was acceptably precise only for participants making a high number of perseverative errors., Conclusions: The PCET precisely measures latent abstraction ability in the Army STARRS sample, especially within the range of mildly impaired to average ability. This precision pattern is ideal for a test developed to measure cognitive impairment as opposed to cognitive strength. The PCET also measures latent set-shifting ability, but reliable assessment is limited to the impaired range of ability, reflecting that perseverative errors are rare among cognitively healthy adults. Integrating cognitive and psychometric models can provide information about construct validity and measurement precision within a single analytical framework.

The neurocognitive processes involved during classic spatial working memory (SWM) assessment were investigated by examining naturally preferred eye movement strategies. Cognitively healthy adult volunteers were tested in a computerized version of the Corsi Block-Tapping Task--a spatial span task requiring the short term maintenance of a series of locations presented in a specific order--coupled with eye tracking. Modeling analysis was developed to characterize eye-tracking patterns across all task phases, including encoding, retention, and recall. Results revealed a natural preference for local gaze maintenance during both encoding and retention, with fewer than 40% fixated targets. These findings contrasted with the stimulus retracing pattern expected during recall as a result of task demands, with 80% fixated targets. Along with participants' self-reported strategies of mentally "making shapes," these results suggest the involvement of covert attention shifts and higher order cognitive Gestalt processes during spatial span tasks, challenging instrument validity as a single measure of SWM storage capacity.

Apathy is a relatively common psychiatric syndrome in HIV infection, but little is known about its neural correlates. In the present study, we examined the associations between apathy and diffusion tensor imaging (DTI) indices in key frontal white matter regions in the thalamocorticostriatal circuit, which has been implicated in the expression of apathy. Nineteen participants with HIV infection and 19 demographically comparable seronegative comparison subjects completed the Apathy subscale of the Frontal Systems Behavioral Scale as a part of a comprehensive neuropsychiatric research evaluation. When compared to the seronegative participants, the HIV+ group had significantly more frontal white matter abnormalities. Within HIV+ persons, and as predicted, higher ratings of apathy were associated with greater white matter alterations in the anterior corona radiata, genu, and orbital medial prefrontal cortex. The associations between white matter alterations and apathy were independent of depression and were stronger among participants with lower current cluster of differentiation 4 (CD4) counts. All told, these findings indicate that apathy is independently associated with white matter abnormalities in anterior, medial brain regions in persons infected with HIV, particularly in the setting of lower current immune functioning, which may have implications for antiretroviral therapy.

Objective: The psychometric properties of the Penn Face Memory Test (PFMT) were investigated in a large sample (4,236 participants) of U.S. Army Soldiers undergoing computerized neurocognitive testing. Data were drawn from the initial phase of the Army Study to Assess Risk and Resilience in Servicemembers (Army STARRS), a large-scale study directed towards identifying risk and resilience factors for suicidal behavior and other stress-related disorders in Army Soldiers. In this paper, we report parallel psychometric and cognitive modeling analyses of the PFMT to determine whether ability estimates derived from the measure are precise and valid indicators of memory in the Army STARRS sample., Method: Single-sample cross-validation methodology combined with exploratory factor and multidimensional item response theory techniques were used to explore the latent structure of the PFMT. To help resolve rotational indeterminacy of the exploratory solution, latent constructs were aligned with parameter estimates derived from an unequal-variance signal detection model., Results: Analyses suggest that the PFMT measures two distinct latent constructs, one associated with memory strength and one associated with response bias, and that test scores are generally precise indicators of ability for the majority of Army STARRS participants., Conclusions: These findings support the use of the PFMT as a measure of major constructs related to recognition memory and have implications for further cognitive-psychometric model development.

Accumulating evidence suggests that working memory load is an important factor for the interplay between cognitive and facial-affective processing. However, it is unclear how distraction caused by perception of faces interacts with load-related performance. We developed a modified version of the delayed match-to-sample task wherein task-irrelevant facial distracters were presented early in the rehearsal of pseudoword memoranda that varied incrementally in load size (1-syllable, 2-syllables, or 3-syllables). Facial distracters displayed happy, sad, or neutral expressions in Experiment 1 (N=60) and happy, fearful, or neutral expressions in Experiment 2 (N=29). Facial distracters significantly disrupted task performance in the intermediate load condition (2-syllable) but not in the low or high load conditions (1- and 3-syllables, respectively), an interaction replicated and generalised in Experiment 2. All facial distracters disrupted working memory in the intermediate load condition irrespective of valence, suggesting a primary and general effect of distraction caused by faces. However, sad and fearful faces tended to be less disruptive than happy faces, suggesting a secondary and specific valence effect. Working memory appears to be most vulnerable to social-emotional information at intermediate loads. At low loads, spare capacity is capable of accommodating the combinatorial load (1-syllable plus facial distracter), whereas high loads maximised capacity and deprived facial stimuli from occupying working memory slots to cause disruption.

Although much is known about working memory (WM) and emotion perception deficits in schizophrenia, little is known of how these deficits interact. We sought to address this gap by conducting a narrative review of relevant literatures and distilling core themes. First, people with schizophrenia have difficulty with high load and during initial phases of WM (e.g., encoding, early rehearsal), yet are able to activate WM-related prefrontal brain regions to the same maximal degree as comparison controls under certain circumstances. Second, people with schizophrenia have difficulty identifying and expressing facial emotions, yet demonstrate heightened automatic/implicit processing of facial emotions. Third, people with schizophrenia behaviourally demonstrate intact cognition-emotion interactions on laboratory tasks wherein emotional processing is automatic/implicit, yet demonstrate cognition-emotion disconnections in other levels of analysis. Insights are drawn from basic science showing interdependency between WM load and implicit emotion. Future research questions are raised regarding interactions between WM load and implicit facial-affective processing in schizophrenia.

This study examined brain asymmetries elicited during visuomotor tracking. Thirty-two healthy participants performed a fixed gaze, dynamic, pinch force, visuomotor tracking task during a functional magnetic resonance imaging study. The dynamic task required the subject to press a rubber bulb with the thumb to trace a cosine square wave varying in force amplitude from 0-500 cN and having a frequency of 1.5 Hz. Response hand order and direction of the stimulus presentation (right-to-left or left-to-right) were permuted across participants. Two forms of functional cerebral asymmetry were observed, hemispheric specialization and homologous lateralized response. The superior portion of the right middle frontal gyrus and the left supplementary motor area appeared specialized for VM tracking regardless of response hand used or stimulus movement direction. Lateralized effects appeared in the primary sensorimotor hand area, putamen, parietal operculum/posterior insula, dentate nucleus of the cerebellum, precuneus, and middle occipital gyrus. These lateralized areas of activation surfaced when either response hand or direction of stimulus movement was manipulated. The VM task used in this study activated asymmetrical neural activity in the vertically organized skelotomotor system and in sensory systems involving visual attention or proprioception.

Lexical decision tasks have been used to study both shifts of attention and semantic processing in Parkinson's Disease (PD). Whereas other laboratories have reported normal levels of semantic priming among PD patients, our laboratory has reported abnormally large levels. In this study, two experiments were performed to determine the influence of task structure on the extent of semantic priming during lexical decision-making and pronunciation tasks among PD patients and neurologically healthy controls. In Experiment 1, the effect of Prime Dominance (the ratio of category to neutral trials) on lexical decision-making was studied. Although equal numbers of word and nonword trials were presented, half of the PD patients and controls were studied under Category Prime Dominance (category : neutral prime ratio of 2:1) and half were studied under Neutral Prime Dominance (category : neutral prime ratio of 1:2). In Experiment 2, PD and control participants were studied on lexical decision-making and pronunciation tasks where twice as many words as nonword trials were presented, consistent with other studies from our laboratory. In Experiment 1, we found no group differences in the magnitude of priming and no effect of Prime Dominance. Moreover, the findings were similar in pattern and magnitude to results published by Neely (1977). In Experiment 2, we observed larger priming effects among PD patients than among controls, but only on the lexical decision (LD) task. These results support the hypothesis that abnormally large category-priming effects appear in LD studies of PD patients when the number of word trials exceeds the number of nonword trials. Furthermore, increased lexical priming in PD appears to be due to processes operating during the decision-making period that follows presentation of the lexical target.

In two published studies, we used a variant of Neely's (1977) lexical decision paradigm to study shifts of attention and automatic lexical activation in nondemented individuals with Parkinson's disease (McDonald, Brown, & Gorell, 1996; Spicer, Brown, & Gorell, 1994). Arnott and Chenery (in press) noticed differences between Neely's results and the results we observed in our control group that raise questions about some of the conclusions presented in the McDonald et al. (1996) and Spicer et al. (1994) papers. Even when considering the important differences between Neely's (1977) results and those in our control groups, we argue that our results support the conclusions of normal automatic semantic activation and deficient set-shifting in Parkinson's disease. We also introduce the notion of generalized priming to account for some of the priming effects observed in our studies.

A meta-analysis (N = 40) of the effects of depression on memory in the elderly (sample mean age > or = 55 years) examined variables potentially accounting for divergent findings in the literature. The distribution of effects was bimodal and the effect sizes were heterogeneous. Compared to controls, groups containing unipolar subjects only were significantly less impaired than were mixed unipolar-bipolar; five of six studies mixing depression subtype were associated with the more negative mode. Samples containing younger depressed subjects (< 45 years) were significantly more impaired and were associated with the more negative mode. Significant group differences were found between studies matching their comparison groups reasonably well on years of education and those that did not. Thoroughness of dementia screening yielded no group differences. Although correlated observations precluded significance tests, larger effects were found for (1) figural (vs. verbal) memory; (2) delayed (vs. immediate) memory; and (3) recognition (vs. free recall and incidental or cued recall; incidental and cued recall effects were nearly identical). Similar effects were found for composite memory scores versus constituent and for various presentation paradigms (e.g., single presentation, selective reminding). Effect sizes for these categories were in the moderate range. Difficulties synthesizing this literature are discussed as are suggested remedies and directions for future research.

Eighty-two Persian Gulf War veterans seen in clinic were referred for neuropsychological evaluation. Relatedness of neuropsychological and neurological functioning to subjective complaint, exposure, a clinical signs index, and possible interference variables was examined in a subsample of 49 who completed assessment. The subsample was representative of the entire group with respect to symptom severity. Variables representing sustained attention, grip strength, motor coordination, vibratory sense, finger-tip number writing perception, executive functioning, memory functioning, and subjective complaint were considered. Neuropsychological performance appeared to be more related to emotional functioning than demographic variables or variables associated with the war. Individual differences may be contributing to different emotional reactions to illnesses, perceptions of exposure risks and cognitive functioning, and responses to stress.

On a lexical decision (LD) task, participants quickly decide whether a target letter string is a word. When a target word (e.g., CARROT) is preceded by a category cue (e.g., VEGETABLE), participants respond more quickly than when the target is preceded by a semantically neutral cue (e.g., BLANK). Previously, Spicer, Brown, and Gorell (1994) reported that patients with PD, when tested with a variation of Neely's (1977) LD task, showed hyperpriming. That is, patients with PD exhibited a larger difference in reaction time between the neutral cue and category prime conditions than did controls. The present study found little evidence that PD hyperpriming was explained by difficulties accessing semantic information. Rather, hyperpriming appeared to be related to a general tendency among a subgroup of patients with PD to perseverate.

Twenty-two nondemented patients with idiopathic Parkinson disease (PD) and 22 controls completed a lexical decision task for which the expected relationship between primes and targets was manipulated. Both reaction times and movement times were measured. PD subjects were as effective as controls in utilizing the priming cues to reduce their reaction times compared with a neutral condition. This facilitation occurred even at the shortest stimulus onset asynchrony employed (300 ms), and was observed in a condition requiring a shift of attention, suggesting that PD patients experience no general cognitive slowing and no difficulty efficiently shifting attention to a specified semantic category. The degree of facilitation was significantly greater in the PD group in several comparisons, indicating hyperpriming. Finally, expectancy primes facilitated movement times in the PD group only. Although the results do not support the existence of generalized bradyphrenia in nondemented Parkinson disease, the hyperpriming effect and correlational analyses involving vocabulary scores and choice reaction time do raise the possibility of a subtle semantic processing deficit or an impairment of strategic decision-making in PD.

An assessment strategy using multiple levels of observation permitted description of problems in everyday living experienced by cerebral revascularization candidates. We contrasted the neuropsychological deficits and real-world dysfunction displayed by candidates for cerebral revascularization with that manifested by patients with severe spinal complaints. Correlations between selected neuropsychological scores and life quality measures were modest. Prediction of real-world performance in individuals likely will require multivariate combinations of measures. Relationships between life quality measures and neuropsychological scores may differ for patients with known or suspected neurological disease and patients with disorders which do not threaten cognitive functioning.

A patient with a discrete, left medial thalamic hematoma developed a severe anterograde amnesia. The memory deficit was most consistent for verbal materials, but was also observed on several tests of figural memory. The patient appeared to have a normal short-term memory (STM) capacity, performed normally on a STM distractor task and was not abnormally sensitive to proactive inhibition. This case is evidence that unilateral damage to the medial thalamus alone can produce a severe memory deficit.

Some authorities have advocated matching tests on several critical psychometric properties before inferring the presence of a differential pattern of deficit. This study examined the effects of lateralized cerebral dysfunction on the matched Verbal and Design subtests of the Continuous Paired-Associate Test (CPAT). Patients with lateralized destructive lesions were studied in Experiment 1. Epileptic patients with lateralized electroencephalographic findings were studied in Experiment 2. Left but not right hemispheric abnormalities impaired performance on the Verbal CPAT, but only for destructive lesions. The Designs CPAT was a nonspecific indicator of cerebral dysfunction. For studies with the goal of predicting laterality of cerebral dysfunction, we advocate a two-step strategy of test development. The first step would make use of the principle of double dissociation in selecting items to compose subtests. The second step would involve an item analysis of subtests to determine the need for matching.

We developed verbal and figural continuous paired associate tests (CPAT) that are matched on internal consistency and on the distributional properties of mean item difficulty, variance, and skewness. The Verbal CPAT is composed of high frequency nouns, verbs, and adjectives. Selection of the designs was guided by literature on the effects of right-hemisphere damage on memory for designs. One hundred subjects were given 80 items from the verbal CPAT and 80 items from the designs CPAT. Twenty subjects at these five ranges of Wechsler Memory Quotient were evaluated: less than or equal to 79, 80-89, 90-99, 100-109, greater than or equal to 109. The final 40-item version of the Verbal CPAT had a mean of 26.72, a SD of 7.03, and an alpha of .859. The Designs CPAT had a mean of 26.42, a SD of 7.75, and an alpha of .886. Neither test was significantly skewed. These matched tests should be useful in making inferences about differences between verbal and figural memory that are not confounded with the problem of differential test sensitivity.

Analysis of Covariance (ANCOVA) is often used in neuropsychological studies to effect ex-post-facto adjustment of performance variables amongst groups of subjects mismatched on some relevant demographic variable. This paper reviews some of the statistical assumptions underlying this usage. In an attempt to illustrate the complexities of this statistical technique, three sham studies using actual patient data are presented. These staged simulations have varying relationships between group test performance differences and levels of covariate discrepancy. The results were robust and consistent in their nature, and were held to support the wisdom of previous cautions by statisticians concerning the employment of ANCOVA to justify comparisons between incomparable groups. ANCOVA should not be used in neuropsychological research to equate groups unequal on variables such as age and education or to exert statistical control whose objective is to eliminate consideration of the covariate as an explanation for results. Finally, the report advocates by example the use of simulation to further our understanding of neuropsychological variables.