A series of experiments will be reported comparing the performance of groups of 11 year old and IS year old children with dyslexia with groups of normal children matched for chronological age (CA) and reading age (RA) respectively. Experiments testing gross motor skill demonstrated that both groups of children with dyslexia showed significant deficits in balance when required to undertake a further task at the same time, whereas the control groups were not affected. It was concluded that the control children balanced automatically whereas the children with dyslexia did not. Further experiments indicated that working memory performance was not diswdered, in that deficits in memory span were paralleled by deficits in speed of articulation. Tests of information processing speed led to an interesting dissociation. Simple reaction performance was indistinguishable from that of the C A controls. By contrast, on the simplest possible choice reaction, both groups of children with dyslexia were slowed to the level of their R A controls. It was concluded that the locus of the speed deficit lay within the decision-making process. Further experiments demonstrating deficits in sensory thresholds and abnormal evoked potentials will also be reported. W e conclude that an auiomatisation deficit is consistent with most of the known problems of children with dyslexia.

Anomalies have been found in a range of skills for children with dyslexia. The study presented here investigated performance on the full range of primitive skills for with dyslexia and normal children at ages 8, 11 and 16 years. Unexpectedly severe deficits were revealed in a range of skills, including motor skill, phonological skill, and processing speed. Overall, the performance of the 16 year old children with dyslexia was no better than that of the 8 year old normal children, with some skills being significantly worse, and some better. The results are inierpteted in terms of a developmental progression in which children with dyslexia suffer from general deficits in primitive skill learning, but are able to consciously compensate in many skills. We believe that a connectionist learning framewcxk may provide a parsimonious account of the range of deficits, providing a potential link between these difficulties in skilled performance and the underlying neuroanatomical abnormalities

Two studies are reported in which a group of adolescent children with dyslexia and a group of normal children matched for age and IQ undertook extended training. In Study 1, which comprised three phases of learning over an 18 month period, the children learned to navigate via key presses around a fixed circuit of a computer maze. It w a s concluded that, following extended training under these optimal conditions, the children with dyslexia had normal 'strength' of automatisation (as assessed by resistance to unlearning, by ease of releaming, and by dual task performance) but that their 'quality' of automatisation (as assessed by speed and accuracy) was impaired. Study 2 investigated the blending of two compatible simple reaction responses into a two choice reaction. Although performance on the simple reactions was equivalent across groups, the children with dyslexia had m o r e difficulty combining the two skills at firstand showed significantly less learning over the course of the training period. T h e estimated learning rate was around 5 0 % slower for the children with dyslexia, leading to the prediction that the proportionate slowing in acquisition time would increase as the square root of the normal acquisition time. A connectionist frameworic may provide a natural explanation of the phenomena.