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Evaluation of the Cellfield intervention for dyslexia : behavioural and electrophysiological outcomes


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Sander, J 2008 , 'Evaluation of the Cellfield intervention for dyslexia : behavioural and electrophysiological outcomes', Research Master thesis, University of Tasmania.

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The current study aimed to contribute to the identification of potential intervention programs
for dyslexia by comparing the effects of one commercial program, the Cellfield intervention, to
those of a placebo program in adolescents with reading and/or spelling difficulties. The
Cellfield intervention is a comprehensive computer-based approach to treating dyslexia, which
involves visual, phonological, and visual-to-phonological exercises. The efficacy of the
intervention was assessed using behavioural (reading, phonological, and spelling measures and
reaction time and accuracy) and electrophysiological (P2, N4, and LPC components of the
ERP) indicators of change. Twelve students (aged between 12 and 14 years) identified as
experiencing reading and spelling difficulties participated, with seven students completing the
Cellfield intervention and five students the placebo program. All participants completed a
variety of reading and literacy tests and phonological and lexical decision tasks and an
incongruent sentence ending task during which event-related potentials (ERPs) were recorded.
All tasks were administered before and immediately after the completion of the Cellfield
intervention and placebo program respectively. Both groups then engaged in a follow-on
practice for three weeks, focusing on training in reading fluency, comprehension, and spelling.
Outcome measures were assessed again after completion of the follow-on training. The
Cellfield group, but not the Placebo group, showed a significant decrease in overall risk for
dyslexia and a significant improvement in phonological decoding skills from pre- to post-test.
These gains in phonological skills were maintained at follow-up for the Cellfield group.
Higher-order literacy skills, including text reading comprehension, accuracy, and fluency did
not change significantly following the Cellfield intervention. However, after the three-week
follow-on practice, the Cellfield and Placebo groups showed significantly improved text
reading comprehension and accuracy from pre- to follow-up-test. Spelling skills remained
unaffected by either the Cellfield intervention or follow-on practice. Results from the ERP
studies were less conclusive. For all three experimental tasks, neither reaction time nor latency
data discriminated the two groups over time. Amplitude data indicated some neural changes within the Cellfield group, who demonstrated decreased amplitudes in the right hemisphere
(LPC), and increased amplitudes in the left hemisphere (N4) from pre-, to post, to follow-uptest
compared to the Placebo group. Increased left lateralised processing and its relationship to
normal language processing are discussed. Overall, reading data suggest some beneficial effects
of the Cellfield intervention. Neural changes due to the Cellfield intervention are tentative and
need further investigation.

Item Type: Thesis - Research Master
Authors/Creators:Sander, J
Keywords: Cellfield (Firm), Dyslexia, Reading disability
Copyright Holders: The Author
Copyright Information:

Copyright 2008 the author

Additional Information:

University of Tasmania. School of Psychology. Theses. Thesis (MSc)--University of Tasmania, 2008. Includes bibliographical references. Ch. 1. Overview of the thesis -- Ch. 2. Dyslexia: an overview -- Ch. 3. Models of normal reading acquisition and visual word recognition -- Ch. 4. Current understanding of dyslexia -- Ch. 5. Neurobiological basis of dyslexia -- Ch. 6. Interventions for dyslexia and their outcomes -- Ch. 7. Rationale and general aims -- Ch. 8. Method -- Ch. 9. Results -- Ch. 10 Discussion

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