Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references (leaves 79-100). Available also in a digital version from Dissertation Abstracts.

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Virtual-reality neuropsychological tests offer a novel way to assess real-life executive functioning within the context of standardized test conditions whilst maximizing ecological validity. Given the limited empirical evidence base for many of these virtual-reality tests, the current study aimed to further examine the relative ecological validity, sensitivity to brain-injury and diagnostic accuracy of the virtual-reality based Jansari assessment of Executive Functions (JEF). To do this, the test was compared to seven standard tests of executive function, in a New Zealand sample of 27 brain-injured and 28 non brain-injured participants matched for age, gender and education. The JEF’s ecological validity was supported, with JEF total percent scores exhibiting large correlations with participants’ independently reported levels of everyday functioning, as measured by the Dysexecutive Questionnaire: Independent-Rater (DEX-IR) and Patient Competency Rating Scale-Relative (PCRS-R) (both rs = 0.606, p < 0.001). Compared to the standard executive function test variables included in the current study, the JEF’s associations with the everyday functioning measures were the largest, but only significantly larger than the respective correlations of some standard executive function test variables. These results indicated that the JEF is trending towards being relatively more ecologically valid than most of the standard executive function tests included in the study. The JEF also exhibited good sensitivity to brain-injury and diagnostic accuracy for discriminating brain-injured from non brain-injured participants, which was generally consistent with most of the standard tests, but only significantly better than some. These results provide empirical support for the JEF’s clinical utility, particularly in the assessment of brain-injured persons’ functional abilities. It also suggests that both virtual-reality and standard executive function tests have a place in the routine neuropsychological test batteries used to assess brain-injured persons.

The impetus behind this investigation was a little-understood syndrome of retarded language development known as developmental dysphasia. Little agreement exists with respect to the characterization of children classified dysphasic, and even less is known regarding the etiology of this problem. One theoretical position postulates a lag in the maturation of systems relevant to language acquisition. A second position is oriented toward specific deficits which impede the development of language skills in some children. An emerging theme ties the difficulties of dysphasic children to some type of cerebral dysfunction. Another issue concerns the scope of the problems of developmentally dysphasic children. The bulk of research in this area focuses on language-related measures although it has been suggested that the difficulties underlying developmental dysphasia may extend to non-language areas. The paucity of studies of non-language abilities of dysphasic children has contributed to conceptualizations of developmental dysphasia as exclusively a language-related problem. The principal aim of this investigation was to attempt to characterize children with developmental dysphasia within a neuropsychological context, evaluating the adequacy of current theories concerning the etiology of developmental dysphasia and looking at the abilities of dysphasic children in non-language areas. A group of children classified as developmentally dysphasic were compared with groups of normal and brain damaged children on measures of language (Reitan-Indiana Aphasia Screening Test), sensory-perceptual (Reitan-Klove Sensory-Perceptual Examination), and motor (Finger Oscillation Test and grip strength) abilities. A scoring procedure was designed which allowed for the qualitative evaluation of responses as they relate to the integrity of brain functions. Results indicated that children with cerebral damage perform more poorly than do control subjects on measures of normal language and sensory-perceptual and motor abilities, showing evidence of abnormalities across all areas. Children in the dysphasic group performed deficiently in the language area and had difficulties in the sensory-perceptual area. Motor performances of children in the dysphasic group, were substandard when compared to the motor abilities of normal children. These results support a theory of brain dysfunction as a contributing factor in the retarded development of language and other abilities in developmentally dysphasic children.

Damage to the brain can affect the core of the individual, i.e. the self. Results from a small number of studies with amnesic individuals indicate that patients' ability to show preserved knowledge of self may vary. The present study explored self-knowledge in patients with memory impairment as a result of confabulation, mild cognitive impairment, Alzheimer's disease and acquired brain damage. We found that different memory disorders differentially affected patients' self-knowledge. At least some patients showed a preserved sense of self, and were able to acquire information about another person that they had met postmorbidly. Frontal function and stability of cognitive impairments over time appear to be two variables important in determining whether patients can have a consistent and updated sense of self. We also explored the extent to which self-referential and other-referential processing might enhance memory in individuals with memory-impairment. The self-reference effect (SRE) and other-reference effect (ORE) have been consistently found in normal adults. Results indicated that patients showed a normal SRE and ORE. The SRE and ORE appeared to be at least partly dependent on degree of knowledge of the person being referenced, and were also related to general memory and frontal function. Only the SRE, however, was also related to patients' ability to improve memory as a result of emotional processing. These findings may have important implications for caregivers and healthcare professionals working with memory-impaired patients, and may pave the way to novel memory rehabilitation methods.

Attention Deficit Hyperactivity Disorder (ADHD) is a relatively common psychiatric disorder affecting 5-10% of child and 4% of the adult population. The disorder involves both behavioural problems and cognitive deficits, which are believed to be associated with neurological differences seen in this population. There has been increasing interest in understanding the cognitive deficits and neurological basis associated with ADHD. Neuropsychological examinations are an affordable tool, which can be used to improve our understanding of the cognitive deficits associated with the disorder and aid in clinical care. Currently, there is no standardized neuropsychological assessment that can be used in this population. In order to assist in developing a sound, predominately computerized test battery, which would assess deficits commonly seen in adults with ADHD, a neuropsychological project was piloted to examine recruitment and test utility. The majority of the tests were computerized and had population norms. The test battery was piloted on 8 patients on and off medication, and 4 patients completed the test battery twice off medication to examine potential practice effects. A discussion of feasibility and utility of the neuropsychological test battery for adults with ADHD ensues.

No abstract available. / Thesis (Ph.D.)-University of Natal, Durban, 1989.

Heterogeneity in children with Attention Deficit Hyperactivity Disorder (ADHD) symptoms is a well-known phenomenon. Empirically, this heterogeneity is evident in at least three different respects: expression of the two ADHD symptom domains (hyperactivity/impulsivity and inattention), neuropsychological impairments, and comorbid behavior problems. The major aim of the present thesis was to examine the heterogeneity characterizing children with ADHD symptoms to enhance our understanding by examining neuropsychological factors with regard to common and independent contributions, and specificity of the two ADHD symptom domains in relation to neuropsychological factors and comorbid behavioral problems. Particular emphasis is placed on prominent neuropsychological processes such as executive functions, state regulation and delay aversion. The present thesis is based on findings from four studies on community-based samples of children – studies involving concurrent and longitudinal designs as well as both categorical and dimensional approaches. Results provide support for the notion that executive function and state regulation, but not delay aversion, constitute independent pathways to ADHD, primarily to symptoms of inattention. However, delay aversion was shown to have an effect in combination with state regulation on both hyperactivity/impulsivity and inattention. Additionally, symptoms of hyperactivity/impulsivity and inattention have different primary correlates concerning neuropsychological factors and comorbidity. More specifically, executive function, state regulation, internalizing problems and academic achievement were specifically related to inattention but not to hyperactivity/impulsivity. Oppositional Defiant Disorder (ODD) was specifically related to hyperactivity/impulsivity, but not to inattention. The present thesis has contributed with important and new knowledge about the heterogeneity of children with ADHD symptoms concerning neuropsychological pathways, and specificity of the two ADHD symptom domains in relation to neuropsychological factors and comorbid behavioral problems. Knowledge such as this can help us understand how to identify more homogeneous ADHD subgroups, and contribute to the further development of multiple pathway models within this area of research.

The 2002 Supreme Court decision (Atkins vs. Virginia, 536 U. S. 304), prohibiting the execution of mentally retarded persons, may potentially increase malingering of mental retardation (MR). There is limited research addressing the detection of feigned MR. The present study compared results from tests of intelligence, adaptive functioning, legal/courtroom knowledge, and psychiatric and neurocognitive feigning to determine how effectively these instruments discriminate between MR participants and community volunteers asked to either approach the test honestly (CVH group) or feign, or malinger, MR (CVM group). CVMs suppressed their IQ scores sufficiently to appear MR. CVMs overestimated deficits on individuals with genuine MR on tests of adaptive functioning and courtroom knowledge. Psychiatric feigning instruments did not discriminate between MR and CVM groups. Neurocognitive feigning instruments discriminated between groups, however specificity and Positive Predictive Power were unacceptably low. Revising cutting scores to hold specificity at .95 improved PPP significantly, suggesting the potential utility of these instruments to detect feigned mental retardation. Results from this study suggest that applying published decision rules to MR populations on tests commonly used in forensic neuropsychological evaluations will likely result in a high rate of false positive errors. Given the high stakes associated with classification errors in capital cases involving MR defendants, alternative cutting scores appropriate for this population should be determined.

A study was conducted, comparing the relationship between the Bender-Gestalt Test and the Trail-Making Test in brain-damaged patients. The study revealed a moderate negative correlation between the scaled score of the Trail-Making Test and the psychopathology scale of the Hutt Adaptation of the Bender-Gestalt Test. This relationship indicates that a number of skills might be tapped by both of these tests in brain-damaged patients. A further analysis showed that the correlation between the Trail-Making Test A and three factors of the Bender-Gestalt Test, Use of Space I, Collision, and Elaboration, were found to be significant (.05). In addition, the Trail-Making Test B is significantly correlated with the following factors of the Bender-Gestalt Tests Sequence, Use of Space I, Collision, Perceptual Rotation, and Retrogression (.05).This investigation discussed a number of skills and abilities which might be important on the performance of these tests in brain damaged patients, namely: anticipatory planning, visual organization, and shifting. Furthermore, overt anxiety has been considered one of the factors which might affect the performance of the brain-damaged patients on both tests.