Magnocellular-dorsal stream functioning and exogenous visual attention in elementary school readers: a longitudinal analysis
Reading difficulty is a common childhood phenomenon. Many children with reading difficulty experience a magnocellular-dorsal stream deficit. This deficit may impair exogenous visual attention (VA) by feeding anomalous information into the posterior parietal cortex, a part of the brain primary responsible for exogenous VA processes. Exogenous VA has an important influence on reading ability and is often impaired in children with reading difficulty. This longitudinal study was designed to illuminate the role of magnocellular-dorsal stream functioning and exogenous VA in reading difficulty, using data from 171 children with varied initial reading abilities tested throughout grades 1, 2, and 3 in public schools. A longitudinal structural equation modelling (SEM) design was utilized to examine the concurrent and predictive relationships of coherent motion detection performance (an index of magnocellular-dorsal stream functioning) and line motion illusion performance (an index of exogenous VA functioning) on reading decoding ability, respectively. The development of these relationships were also examined over time. The best fitting model showed evidence of persistent relationships between VA and early reading ability, and a predictive effect between exogenous VA at the earliest time point and subsequent reading performance. This implies that although VA influences reading growth only during early reading acquisition, reading decoding achievement at very early periods in development can have longer term influences on developing visual processes, emphasizing the importance of reading in the beginning stages. Results contribute to knowledge about the longitudinal associations between VA processes and reading ability and provide evidence for remediating VA difficulties in children with reading difficulty.
Magnocellular-dorsal stream, Posterior parietal cortex, Coherent motion detection, Exogenous visual attention, Line motion illusion, Reading difficulty