The reading and oral language scores of 110 children with a specific reading disability (SRD) and 102 children with a specific language impairment (SLI) indicated that approximately 53% of children with an SRD and children with an SLI could be equally classified as having an SRD or an SLI, 55% of children with an SRD have impaired oral language, and 51% of children with an SLI have a reading disability. Finding that a large percentage of children can be equally classified as SRD or SLI has repercussions for the criteria used to define an SRD, for conceptualising subgroups of learning disability, and for estimates of the incidence of SRD. Further, it highlights the need for future studies to assess both the reading and oral language abilities of SRD and SLI participants to determine how specifically impaired and homogeneous samples really are.

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Inferior auditory temporal processing has been postulated as causally linked to phonological processing deficits in disabled readers with concomitant oral language delay (LDRDs), and absent in specifically disabled readers with normal oral language (SRDs). This investigation compared SRDs, LDRDs and normal readers aged 7-10 years on measures of auditory temporal processing (temporal order judgement) and phonological decoding (nonword reading). LDRDs exhibited deficits in temporal order judgement compared with normal readers, from whom SRDs did not differ significantly. These findings suggest that auditory temporal processing and oral language are related; however, very large within-group variability in the auditory temporal processing data further suggests that this relationship prevails in only a proportion of disabled readers with concomitant oral language weakness. In nonword reading, LDRDs performed worst of all, but SRDs also exhibited significant deficits compared with normal readers. Taken together, our results preclude the conceptualisation of temporal processing deficits as the unitary cause of phonological and language deficits in disabled readers.

Phonological processing has been shown by many researchers to be strongly related to the acquisition of reading and spelling skills. Children with speech and language impairment appear to be at increased risk for phonological processing problems and hence literary difficulties. However, not all children with speech and language impairment experience difficulties: the literature is not clear as to which groups of speech and language impaired children are most severely affected nor which aspects of phonological processing are most likely to be impaired. Rigorous subject selection was employed to compare the performance of four groups of 20 children, aged approximately 6 years: speech-impaired (Speech); language-impaired (Language); speech and language impaired (Mixed); and children with normally developing language (Normal), by use of a battery of phonological processing tasks. The results supported the research that has shown speech and language impaired children to have weaker phonological processing skills than the general population. All the subjects in this sample appeared to be at risk: the Mixed children demonstrated the most difficulty, followed by the Language group, with the Normal group performing the best. Whilst the Speech group as a whole performed significantly more poorly than the Normal group, it consisted of two levels of performance which, on post hoc analysis were shown to relate to the pattern of speech impairment exhibited by the child.

A recent proposal suggests that dyslexic individuals suffer from attentional deficiencies, which impair the ability to selectively process incoming visual information. To investigate this possibility, we employed a spatial cueing procedure in conjunction with a single fixation visual search task measuring thresholds for discriminating the orientation of a target stimulus. Replicating preliminary findings in an earlier report, we found evidence of a striking dissociation between dyslexic participants' performance in cued and uncued conditions. Whereas uncued search results were equivalent for dyslexic and normal adult readers, the majority of dyslexic individuals failed to display a comparable benefit when the location of the target was indicated by the appearance of a brief peripheral pre-cue. Using receiver operating characteristic curve analysis, we further demonstrate that the effectiveness of the cueing task at discriminating between dyslexic and normal readers surpasses that of a range of other psychophysical tasks typically used in dyslexia research. Moreover, we find that the discriminative accuracy of the task is at least on par with measures of verbal short-term memory (a core component of phonological processing), which ranks as one of the most widely accepted areas of difficulty in dyslexia. Potential mechanisms underlying the cueing effect are outlined, and the plausibility of each considered within a signal detection theory framework of visual search. It is argued that performance benefits obtained by normal readers in cued conditions most likely reflect the prioritization of target information during decision making, and could feasibly be subserved by top-down biasing effects on pooling processes in extrastriate cortex.