Dyslexia : challenging theories.

Experiments presented challenge theories on their ability to provide causal explanations of the pattern of performance in dyslexia. Studies la and 1 b employed a prism adaptation paradigm to investigate the Cerebellar Deficit Hypothesis (CDH). No group differences were found, although unfortunately it was concluded that the paradigm could not satisfactorily isolate cerebellar function from other compensation mechanisms. Studies 2a and 2b exploited a sequential stereopsis technique to test the visual deficit hypothesis. No group differences were found, although the dyslexic group did exhibit a fatigue effect on one condition. Using an attention shifting paradigm, Study 3 found a dissociation between focus and shift attention conditions in dyslexic children, but that they sustained their attention as well as controls. In Study 4, supporting the Dyslexia Automatisation Deficit (DAD) as opposed to a general resources deficit, control performance suffered most under visually degraded conditions of the same attention paradigm. Study 5 further investigated attention on a test thought to be sensitive to attentional lapses; dyslexic children did make more errors, although conclusions were limited by their qualitatively normal performance. Deficits in dyslexia were found to be wider reaching than many theories of dyslexia would suggest. At a cognitive level of explanation the DAD was able to account successfully for many of the findings. However, like the Phonological Deficit Theory the DAD specifies no neurological mechanism for the deficit; this is provided by the CDH (for which no evidence was found here). Analyses do point towards the need for either a very general explanation, or the identification of a smaller number of core deficits, for the apparently disparate deficits found. The fatigue effect found only in the dyslexic group on part of the vision experiment has further direct and immediate implications for future research

Studies of visual functions and the effect of visual fatigue in adults with dyslexia

To date, it appears that many studies on dyslexia and its visual correlates are concentrated on children and there are only a few studies examining adult groups with dyslexia. This PhD introduces new knowledge about an adult population (university students) with dyslexia and those dyslexics who diagnosed with Meares-Irlen syndrome, compared to adults with normal reading abilities. Given that a common support strategy at undergraduate level is the provision of extra time in examinations, studies will focus on the effects of fatigue on binocular instability and ocular dominance amongst these cohorts.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Studies of visual functions and the effect of visual fatigue in adults with dyslexia.

To date, it appears that many studies on dyslexia and its visual correlates are concentrated on children and there are only a few studies examining adult groups with dyslexia. This PhD introduces new knowledge about an adult population (university students) with dyslexia and those dyslexics who diagnosed with Meares-Irlen syndrome, compared to adults with normal reading abilities. Given that a common support strategy at undergraduate level is the provision of extra time in examinations, studies will focus on the effects of fatigue on binocular instability and ocular dominance amongst these cohorts

Beyond four dyslexia paradigms: an alternative perspective on dyslexia and emancipatory intervention on self-concept

This study postulates that there are currently four main dyslexia paradigms. These paradigms are: a) the Positivist-Intrinsic-Dyslexia-Paradigm, which reflects positivist studies on dyslexia that hold the etiological view that dyslexia exists intrinsically to the individual (of constitutional origin), b) the Interpretivist-Intrinsic-Dyslexia-Paradigm, which holds the etiological view that dyslexia exists intrinsically to the individual c) the Positivist-Extrinsic-Dyslexia-Paradigm, which reflects studies on dyslexia that hold the etiological view that dyslexia exists extrinsically to the individual (not of constitutional origin), and, d) the Interpretivist-Extrinsic-Dyslexia-Paradigm, which reflects studies on dyslexia that also hold the etiological view that dyslexia exists extrinsically to the individual. This study moves beyond the four main dyslexia paradigms by combining the I-E-D-Paradigm with elements of Burrell and Morgan's (1979) sociological Radical Humanist Paradigm, thus creating a Radical I-E-D-Paradigm from which to conduct the present study. From the position of a Radical I-E-D-Paradigm this study develops an alternative perspective on dyslexia, i.e., a non-constitutional perspective on dyslexia (N-C-PoD), and, emancipatory intervention aimed at assisting 'dyslexic' students to explore their perceptions of dyslexia. This study explores the influence that the N-C-PoD and emancipatory intervention has on the descriptions of dyslexia, in relation to self-concept, of two 'dyslexic' students studying in tertiary education

The Situational Judgment Test: Cognition, Constructs and Criterion Validity

The Situational Judgment Test (SJT) is a personnel selection test in which a hypothetical scenario is provided, and the applicant asked to choose one or rate multiple answers. Unlike conventional knowledge tests, performance does not rely upon typical academic intelligence. A key requirement of research is to fully understand the construct validity, criterion validity and SJT theory. This thesis is a set of 3 studies that investigates firstly, the construct validity of an SJT in medicine, secondly, establishes a new construct of interest to the SJT (formal operational thought, FOT) and thirdly, investigates FOT in relation to both the construct and criterion validity of an SJT in medicine. In study 1 a current model of the construct validity of the SJT was examined alongside two measures assessing individual differences that are not currently included in SJT theory (‘Need for Cognition’ and ‘Occupational Self-Efficacy’) with the aim of increasing the amount of variance explained in SJT scores. Neither existing theory nor the additional variables significantly explained SJT performance. Inspection of the literature revealed aspects of intelligence previously unexplored in relation to the SJT; fluid intelligence and FOT. A new measure of FOT was validated and FOT was conceptualised as a higher level ability for complex reasoning, independent to that used for primary cognitions. Study 3 then assessed FOT, SJT performance, academic attainment and job performance within medical students. FOT scores did not significantly explain variance in the SJT scores. However, they had incremental validity over the SJT in explaining actual job performance. The studies demonstrate that introducing FOT yielded additional unique variance over the SJT when explaining job performance and that this concept is a higher level thought store, independent of procedural and declarative knowledge stores. These ideas are presented in a theoretical model integrating existing intelligence and SJT theory

A semiotic perspective on the positive transfer of L1 structure in second language instruction

Language educators are re-examining the benefits of positive transfer. As the usage of the term language interference is misleading, the benefits of positive transfer have not been fully recognized until recently. When considered from a semiotic perspective with reference to language acquisition, neurolinguistic and applied linguistic theories, language interference can be perceived as a symptom of equivocal signs. It is proposed that student's learner errors may be attributed to a phenomenon called `semiotic confusion', which is a specific state of disorientation caused by a misinterpretation of signs. Consequently, language interference is redefined as a symptom of `semiotic confusion'. A hypothetical model, the Personal Semiotic Cultural Consciousness/ Semiotic Cultural Consciousness (PSCC/SCC), which is composed of two competing states of consciousness that correspond with synthetic and analytic brain functioning provides instructors with insights about the importance of activating their students' internal and external semiotic cultural consciousness through somatosensory signs such as colour

Speech segmentation and spelling skills in children with developmental verbal dyspraxia

The thesis investigates the relationship between spoken and written language difficulties. Two children aged eleven and twelve years were studied. Both were of average intelligence but had a persisting speech difficulty of a dyspraxic nature. Normal control data was collected on each area tested so that the casescould be viewed from a developmental perspective. First, a detailed analysis of speech errors was carried out. Compared to Articulation Age matched controls, the speech disordered children made multiple errors, had difficulty assembling the articulatory programme for unfamiliar words and relied upon word specific knowledge. Second, on tests of auditory discrimination, lexical decision and segmentation skills, the speech disordered children performed less well than Reading Age matched controls. Their difficulties were most pronounced in the auditory modality and when non word material was used. Third, their reading and spelling performance was compared to low Reading Age dyslexic children without obvious speech difficulties. The speech disordered children were more deficient in their use of phonological strategies and had not broken through to the alphabetic phase of literacy development. The cases were followed up after three years. Although the children had improved their performance quantitatively, they still exhibited the same pattern of errors overall. They had become "trapped" in the logographic phase of literacy development and were adopting compensatory strategies when reading and spelling. Their pervasive phonological difficulties were compounded by their inconsistent and incoordinated speech. These findings challenge the traditional view of Developmental Verbal Dyspraxia as a motor speech disorder. In addition to their articulatory difficulties, the children also had auditory processing and lexical problems. The findings allow further discussion of the role of articulatory and phonological skills in literacy development. A model of reading and spelling strategies is presented and the points where speech and language disordered children are most at risk, are indicated. Finally, the clinical, educational and research implications are outlined