Visual and auditory temporal information processing in young children

With this project we aim to investigate the influence of low-level auditory and visual sensory processing on the development of reading and spelling skills. According to the general magnocellular theory, deficient literacy development (dyslexia) might be the behavioural consequence of dysfunctional processing of transient and dynamic changing stimuli. In the auditory modality, a temporal processing deficit has been hypothesized to interfere with the accurate detection of the rapid acoustical changes in speech. Consequently, this subtle speech perception problem might cause a cascade of effects, starting with the disruption of normal development of the phonological system and resulting in problems learning to read and spell. Alternatively, extensive research also suggests the existence of an analogous visual temporal processing deficit in subjects with dyslexia, namely in the magnocellular system, affecting the development of orthographic skills and subsequent reading and spelling skills. This general magnocellular theory, suggesting a cross-modal temporal information processing deficit in subjects with dyslexia, postulates that the sensory deficit might be causally related to the observed phonological, orthographic and literacy problems. However, this causal relation has never been evaluated empirically. In this study we want to address this issue. In a longitudinal study we follow up 31 preschool children with a family history of dyslexia and 31 low risk control children. Participants are individually matched for gender, age, nonverbal IQ, school environment and parental educational level. Both at preschool and at first-grade age we collect multiple measures for auditory and visual processing, speech perception, phonological ability, orthography and reading and spelling skills. Auditory and visual processing is measured using psychophysical threshold tests embedded within a computer game. Auditory thresholds are estimated for (within and between channel) gap-in-noise detection, 2 Hz frequency modulation detection and tone-in-noise detection. Visual thresholds are estimated for the detection of motion coherence in random dot kinematograms. For speech perception we administer a speech-in-noise test and a categorical perception test. Phonological skills are measured by tasks assessing phonological awareness, rapid automatic naming and verbal short term memory. Orthography is measured by a letter knowledge task and a pseudohomophone task. Reading and spelling ability is assessed by multiple standardised and self-constructed tests. Data will be analysed using Mixed Model Analysis comparing the genetically high risk versus low risk group. Furthermore, based on the first grade reading and spelling scores, children will be classified in a normal reading and a reading disabled (dyslexic) group and data will be retrospectively reanalysed comparing these both groups. Concurrent and predictive relations between variables will be explored calculating Spearman correlations and factor analyses. Finally, we aim to integrate all variables within a causal path model using confirmatory factor analysis.status: publishe