This study examined the effects of the second level (intermediate acoustical processing of rhyming words) and the third level (deep-semantic processing of words in sentences) of "levels of processing" framework on memory performance of four types of students (52 "normal" students, 50 students with learning disabilities, 25 students with mild mental handicap, and 25 students with emotional handicap). Statistical analysis revealed that "normal" students and students with emotional handicap performed significantly higher than students with mild mental handicap. However, the analysis did not reveal significant differences among "normal" students, students with learning disabilities, and students with emotional handicap. Nor were there significant differences between students with learning disabilities and those with mild mental handicap. Further, the statistical analysis revealed that the interaction among the four groups of students, encoding levels of processing, and types of retrieval cues was not significant. However, a significant interaction was found between types of retrieval cues and encoding levels of processing. The data on the memory test showed that the mean number correct for all students was the highest when stimulus words were presented and encoded semantically and retrieved using a congruent semantic cue. A mismatch between encoding processing conditions and retrieval cues produced poor memory performance regardless of levels of processing. The findings indicate that appropriate use of levels of processing, congruity, and encoding specificity for retrieval cues enhances recall of information. Recommendations for classroom instructions and future research are discussed. / Department of Special Education

The purpose of the study was to examine the utility of profile analysis using the SCAD index of the Wechsler Intelligence Scale for Children-Third Edition (WISC-III) and behavioral rating scales as brief and accessible elements of a standard neuropsychological battery by which to screen for deficits or assets within the interface between attention, executive functions, and working memory. An ancillary purpose was to examine the further role and diagnostic efficacy of using a continuous performance test of vigilance as a discriminating measure between specific clinical groups. Three subtypes of individuals referred to a diagnostic assessment clinic were identified by means of a three-stage cluster analysis in a sample of 86 children and adolescents on the basis of scores attained on specific neuropsychological, cognitive, and behavioral variables. It was also found that the assigned clusters exhibited a high degree of consistency with the individual diagnoses ultimately rendered during the evaluation. The variables which best discriminated the three subtypes were identified through a forward stepwise discriminant analysis and subjected to multiple validation procedures. The significant and discriminating variables included the SCAD Index, the Attention Problems and Hyperactivity scales of the Behavioral Assessment System for Children (BASC) and the Perceptual Organization factor of the WISC-III. It was also determined that the overall index and a time-related measure from the Conners' Continuous Performance Test (CCPT) were indeed able to differentiate clinical groups. Functional and theoretical implications were addressed in terms of their relevance for examining the interface between attention, executive functions, and working memory as well as for the identification and treatment of those diagnosed with ADHD and LD, or individuals considered to be gifted or intellectually advanced. / Department of Educational Psychology

Baddeley and Hitch (Baddeley & Hitch, 1974) have described a model of working memory which explains how information can be temporarily held `on-line' in order to carry out everyday cognitive tasks such as learning, reasoning, and comprehension. One component of this model, the visuospatial sketchpad (VSSP), has not been as well described as other components of the model and there is some debate over its structure. Furthermore, the everyday cognitive importance of the VSSP has not been well researched. A battery of visual and spatial measures was developed to investigate the structure of the VSSP and its potential role in reading. A principal component analysis on a group of normal, undergraduate participants did not reveal the expected dissociation of visual from spatial processing. However, a dissociation was found in a group of dyslexic individuals. A series of multiple regressions revealed that while neither visual nor spatial processing reliably contributed to reading ability in normals, spatial processing contributed to reading fluency in the dyslexic sample. These findings suggest that while shared variance techniques fail to reveal the visual vs. spatial dissociation in working memory in normals, the dissociation can be revealed by clinical samples. In general, it appears that the ability to maintain visual vs. spatial information in working memory requires distinct cognitive processes. Furthermore, there is a relationship between VSSP processing and reading. This study has opened many doors for future research on the structure of the model and its importance for reading.

The construct of cognitive control is often invoked to provide a mechanism responsible for information-processing in ill-defined situations. However, the dual-mechanism theory of cognitive control distinguishes between proactive and reactive varieties, and provides a more concrete framework for explaining behavior across various conditions. Importantly, although proactive and reactive control have been theorized to apply to differential performance observed in various clinical and aging populations, no empirical work has been conducted examining how this theory may apply to individual differences in working memory capacity within a young, healthy population. The current research directly assessed proactive versus reactive control by administering three versions of the AX version of the continuous performance test to individuals varying in working memory capacity. Across the task versions, specific trial type frequencies were manipulated to examine whether this variable interacted with WMC to cause individuals to engage in one control type over the other. In addition, the current work investigated whether individuals can change their mode of control on a trial-to-trial basis, something that had not previously been examined. Individuals low in working memory capacity exhibited specific performance deficits relative to the individuals high in working memory capacity. The results extend the application of the dual-mechanism theory to individual differences in working memory capacity and provide a theoretical framework to explain previous findings in the working memory capacity literature.

A dominant theory in the anxiety-working memory literature is the Processing Efficiency Theory (Eysenck & Calvo, 1992). According to this theory, worry - the cognitive component of state anxiety - pre-empts capacity in the central executive and phonological loop components within Baddeley and Hitch's (1974) fixed-capacity working memory system. Central to the Processing Efficiency Theory is the distinction between performance effectiveness (i.e. quality of performance) and processing efficiency (i.e. performance effectiveness divided by effort), with anxiety proposed to impair efficiency to a greater extent than it does effectiveness. The existing literature has provided support for this theory, although there exist factors that complicate the findings, including the nature of the working memory tasks utilised, comorbid depression, and the distinction between trait and state anxiety. Clarification of the limiting factors in the anxiety-working memory literature was sought over a series of initial methodological studies. The first study was an initial step in addressing the issue of comorbid depression, identifying measures that maximised the distinction between anxiety and depression. The second study identified verbal and spatial span tasks suitable for examining the various working memory systems. The third study considered a possible role for somatic anxiety in the anxiety-working memory relationship, and additionally addressed the state/trait anxiety distinction. These three initial studies culminated in the fourth study which formally addressed the predictions of the Processing Efficiency Theory, and explored the cognitive/somatic anxiety distinction more fully. For the third and fourth studies, high and low trait anxious individuals underwent either cognitive (ego threat instruction) or somatic (anxious music) stress manipulations, and completed a series of span tasks assessing all components of the working memory system. Unexpectedly, the fourth study yielded a notable absence of robust effects in support of the Processing Efficiency Theory. A consideration of the research into the fractionation of central executive processes, together with an examination of tasks utilised in the existing literature, suggested that anxiety might not affect all central executive processes equally. Specifically, the tasks utilised in this programme of research predominantly invoke the process of updating, and it has recently been suggested that anxiety may not actually impair this process (Dutke & Stober, 2001). This queried whether the current conceptualisation of the central executive component as a unified working memory system within the PET was adequate or if greater specification of this component was necessary. One central executive process identified as possibly mediating the anxiety-working memory relationship is that of inhibition, and the focus of the fifth study thus shifted to clarifying this more complex relationship. In addition to one of the verbal span tasks utilised in the third and fourth studies, the reading span task (Daneman & Carpenter, 1980) and a grammatical reasoning task (MacLeod & Donnellan, 1993) were also included. Inhibitory processing was measured using the directed ignoring task (Hopko, Ashcraft, Gute, Ruggerio, & Lewis, 1998). This study established that inhibition was affected by a cognitive stress manipulation and inhibition also played a part in the anxiety-working memory link. However other central executive processes were also implicated, suggesting a need for greater specification of the central executive component of working memory within the PET. A finding that also emerged from this, and the third and fourth studies, was that situational stress, rather than trait or state anxiety, was predominantly responsible for impairments in working memory. Finally, a theoretical analysis placing the anxiety-working memory relationship within a wider context was pursued, specifically examining how the Processing Efficiency Theory is nested within other accounts examining the relationship between mood and working memory. In particular, similarities between the theoretical accounts of the relationships between anxiety and working memory, and depression and working memory, suggest the operation of similar mechanisms in the way each mood impacts on performance. Despite the similarities, potential distinctions between the impact each has on performance are identified, and recommendations for future research are made.

Thesis (Ph. D.)--University of Oregon, 2007. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 66-73). Also available for download via the World Wide Web; free to University of Oregon users.

Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.

Thesis (Ph.D.)--Baylor University, 2008. / Includes bibliographical references (p. 76-87).

Thesis (PhD) - Swinburne University of Technology, Brain Sciences Institute, 2007. / A thesis for Doctorate of Philosophy, Brain Sciences Institute, Swinburne University of Technology - 2007. Typescript. Bibliography: p. 245-285.

Thesis (Ph. D.)--University of Washington, 2008. / Vita. Includes bibliographical references (leaves 91-106).