A Role for Visual Processing Speed in Cognitive Development in Early School Years

Abstract

Speed of visual information processing is known to play a fundamental role in the development and efficacy of most cognitive functions including working memory and intelligence. However, the extent to which visual information processing and brain development contributes to cognitive maturation in early school years is less clear. Hence, the current project aimed to integrate and systematically review the current literature of cognitive psychology and developmental cognitive neuroscience regarding cognitive development in children under 7 years of age, and then to explore the development of visually driven information processing and its association with age, working memory (WM) and nonverbal intelligence using Structural Equation Modelling. The first study aimed to examine the developmental changes in rates of visual processing speed (PS) on simple and more complex visual tasks related to reading (Rapid Automatic Naming of objects [RAN]) and writing (timed eye hand co-ordination tracing of ‘SLURP’ shapes) and Raven’s nonverbal intelligence (NVI) in a sample of 5 to 7 year old children, and showed that visual PS and NVI improves concurrently with age, with years of schooling providing additional contributions to performance on the RAN and SLURP tasks. The aim of the second study was to investigate the contribution of visual PS to visual and auditory WM, and provides evidence that although both visual and auditory aspects of WM increase with age and brain development, visual PS does not play a significant part in auditory semantic WM development. The last study investigated the association between visual PS and visually assessed WM in predicting NVI. The results support the developmental cascade hypothesis and show an indirect contribution of visual PS to NVI via visual WM development. In conclusion, the cognitive literature relating to development in young school age children can be interpreted in terms of visually driven attention, with lower performance on visual rather than auditory digit span being limited by of lack of orthographic knowledge and RAN and SLURP tasks as used in the current thesis are likely to be useful measures for the early identification of children who are at risk of learning difficulties.