The present study focuses on examining the hypothesis that auditory temporal perception deficit is a basic cause for reading disabilities among dyslexics. This hypothesis maintains that reading impairment is caused by a fundamental perceptual deficit in processing rapid auditory or visual stimuli. Since the auditory perception involves a number of mechanisms and temporal processing is only one of them, in the current paper, we tested, in addition to auditory temporal processing, also auditory intensity and spectral processing among dyslexic and normal readers. In addition, we examined whether poor performance of dyslexic readers in auditory temporal processing tasks results from a difficulty in working memory, by testing differences in auditory processing, controlling for working memory.Thirty-seven adult dyslexic readers and 40 adult normal readers performed a battery of tests measuring auditory temporal processing (gap detection and dichotic temporal order judgment), auditory intensity processing (absolute threshold and intensity discrimination), auditory spectral processing (spectral temporal order judgment) and working memory (backward digit span). Performance on auditory spectral and temporal processing task was poorer among dyslexic readers, as compared to normal readers, even after controlling for working memory, but no difference was found in intensity processing tasks. These results suggest that dyslexic readers exhibit a specific deficit in auditory temporal processing, which cannot be attributed either to general perceptual deficit in auditory processing, or to working memory.

The present study investigates the performance of persons with reading disabilities (PRD) on a variety of sequential visual-comparison tasks that have different working-memory requirements. In addition, mediating relationships between the sequential comparison process and attention and memory skills were looked for. Our findings suggest that PRD perform worse than normally achieving readers (NAR) when the task requires more than a minimal amount of working memory, unrelated to presentation rate. We also demonstrate high correlations between performance on the task with the most working-memory demands and reading-related skills, suggesting that poor working-memory abilities may be one of the underlying mechanisms of dyslexia. The mediating model analysis indicates that order judgment tasks are mediating to verbal working memory, suggesting that visual sequence memory precedes auditory sequence memory. We further suggest that visual tasks involving sequential comparisons could probe for poor working memory in PRD.

Dyslexia is a neuro-cognitive disorder with a strong genetic basis, characterized by a difficulty in acquiring reading skills. Several hypotheses have been suggested in an attempt to explain the origin of dyslexia, among which some have suggested that dyslexic readers might have a deficit in auditory temporal processing, while others hypothesized that dyslexia origins from a deficit in working memory. The current study was designed to test whether working memory and/or auditory temporal processing can predict reading ability in normal and dyslexic readers. Fifty-three adults were diagnosed with phonological dyslexia and 46 normal reading adults were tested on reading regular words, auditory temporal order judgment, and backward digit span. The results are that: For dyslexic readers, both auditory temporal processing and working memory are correlated with reading, even after controlling for their covariance. However, no correlation between reading measures, temporal processing and working memory are found for normal readers. The conclusions are that: (1) Both auditory temporal processing and working memory are significantly involved in reading among dyslexic readers; and (2) Dyslexic readers might use more different reading strategies than normal readers do, who apparently are not involved in auditory temporal processing and working memory while reading.

Developmental dyslexia is a language-based learning disability with frequently associated non-linguistic sensory deficits that have been the basis of various perception-based theories. It remains an open question whether the underlying deficit in dyslexia is a low level impairment that causes speech and orthographic perception deficits that in turn impedes higher phonological and reading processes, or a high level impairment that affects both perceptual and reading related skills. We investigated by means of contrast detection thresholds two low-level theories of developmental dyslexia, the magnocellular and the fast temporal processing hypotheses, as well as a more recent suggestion that dyslexics have difficulties in sequential comparison tasks that can be attributed to a higher-order deficit. It was found that dyslexics had significantly higher thresholds only on a sequential, but not a spatial, detection task, and that this impairment was found to be independent of the inter-stimulus interval. We also found that the poor performance of dyslexics on the temporal task was dependent on the size of the required memory trace of the image rather than on the number of images. Our findings do not support the magnocellular theory and challenge the fast temporal deficit hypothesis. We suggest that dyslexics may have a higher order, dual mechanism impairment. We also discuss the clinical implications of our findings.

While the mental and physical benefits of motor activity are well documented, the degree to which these benefits are dependent upon the environment within which the activity takes place remains unknown. Specifically, studies exploring the effects of aquatic motor activities on cognitive abilities are rare. The current study investigated the effects of aquatic motor activities-as compared to on-land motor activities and non-motor activities-on the development of motor and cognitive abilities in a sample of 94 children aged between four and six. Developmental-functionality testsincluding fine and gross motor, time estimation, reasoning and processing speed tests-were used to measure the motor and cognitive abilities of participants before and after six months of intervention. Participation in the aquatic motor activities group was found to improve gross motor, time-estimation and reasoning abilities. Moreover, improvements in gross motor abilities mediated the association between participation in aquatic motor activities group and the children's processing speed ability. These findings can improve the understanding of child development professionals, psychologists and educators regarding the connection between aquatic environment and cognitive and motor development, and may contribute to improved early childhood interventions.