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Dyslexic Adults (dyslexic + adult)

Distribution by Scientific Domains

Psychology	80%

Selected Abstracts

Exploring dyslexics' phonological deficit I: lexical vs sub-lexical and input vs output processes

DYSLEXIA, Issue 4 2005
Gayaneh Szenkovits
Abstract We report a series of experiments designed to explore the locus of the phonological deficit in dyslexia. Phonological processing of dyslexic adults is compared to that of age- and IQ-matched controls. Dyslexics' impaired performance on tasks involving nonwords suggests that sub-lexical phonological representations are deficient. Contrasting nonword repetition vs auditory nonword discrimination suggests that dyslexics are specifically impaired in input phonological processing. These data are compatible with the hypothesis that the deficit initially affects input sub-lexical processes, and further spreads to output and lexical processes in the course of language acquisition. Further longitudinal research is required to confirm this scenario as well as to tease apart the role of the quality of phonological representations from that of verbal short-term memory processes. Copyright © 2005 John Wiley & Sons, Ltd. [source]

An evaluation of a visual biofeedback intervention in dyslexic adults

DYSLEXIA, Issue 1 2005
Elizabeth Liddle
Abstract A prototype of a biofeedback system designed to treat dyslexia by improving heart-rate variability was evaluated in a single blind study of dyslexic adults. Treatment consisted of four 15 minute exposures to a visual display synchronized with either the participant's own cardiac cycle (intervention condition), or of a synthesized cardiac cycle (placebo condition). Repeated measures were made of picture naming speed, single word reading speed and accuracy, copying speed, heart-rate variability and performance on a lateralized visual temporal order judgement task. Small but significant improvements were found in reading and naming speed in the treatment group relative to the placebo group. No significant improvements were found in unspeeded reading measures. Results from heart-rate measures indicated that treatment had effected a shift in the ratio between parameters reflecting the influence of the sympathetic and parasympathetic autonomic nervous systems (ANS), respectively, in favour of the parasympathetic. In the temporal order judgement task, participants who received treatment showed a reduced level of overall improvement relative to that seen in those who received placebo, coupled with evidence of a shift in visual attention from left to right hemifield in their pattern of performance. The results are interpreted as indicating that the treatment induces a shift in autonomic balance in favour of the parasympathetic ANS, and that this shift is also reflected in increased efficiency of left cerebral hemisphere circuits implicated in the perceptual-motor processes required for naming and reading fluency. Conversely, it is also reflected in lower spatial awareness of peripheral visual stimuli, particularly those presented to left hemifield. Copyright © 2004 John Wiley & Sons, Ltd. [source]

Auditory sensory memory disorder in dyslexic adults as indexed by the mismatch negativity

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 6 2003
T. Kujala
Abstract Deficient temporal discrimination and vulnerability to masking effects caused by rapidly succeeding or simultaneous sounds might be one factor underlying the phonological difficulties in dyslexia. We evaluated cortical auditory discrimination in dyslexia by recording the mismatch negativity (MMN) for a simple pitch change, for an order reversal of tone pairs, and for tone-pair order reversals, with a third tone either preceding or following the tone pairs. It was found that when an additional tone followed the pairs the MMN amplitude was attenuated, suggesting elevated backward-masking effects in the auditory cortex of dyslexic individuals. In addition, the MMN elicited by pitch change was diminished over the left hemisphere of the dyslexic individuals suggesting left hemisphere auditory dysfunction. These results suggest impaired cortical discrimination of sounds and lowered tolerance for the masking effects of rapidly following sounds in dyslexia. [source]

Basic auditory dysfunction in dyslexia as demonstrated by brain activity measurements

PSYCHOPHYSIOLOGY, Issue 2 2000
Teija Kujala
Although the generality of dyslexia and its devastating effects on the individual's life are widely acknowledged, its precursors and associated neural mechanisms are poorly understood. One of the two major competing views maintains that dyslexia is based primarily on a deficit in linguistic processing, whereas the other view suggests a more general processing deficit, one involving the perception of temporal information. Here we present evidence in favor of the latter view by showing that the neural discrimination of temporal information within complex tone patterns fails in dyslexic adults. This failure can be traced to early cortical mechanisms that process auditory information independently of attention. [source]