The Directionality of the Relationship Between Left Hemisphere Lateralization for Word Reading and High Spatial Frequency Visual Information

Studies show that emerging left hemisphere lateralization for word reading is correlated with emerging left hemisphere lateralization for high spatial frequency (HSF) information. However, it is currently unclear whether left lateralization is partially caused by a pre‐ existing left hemisphere bias for high spatial frequency visual information (such as that found in words), or if the left hemisphere tuning for HSF is a consequence of reading experience. This study seeks to determine whether lateralization for HSF information exists prior to left lateralization for reading. We use a divided visual field task to examine left hemisphere bias for words and for high spatial frequency Gabor patches in pre‐readers, early readers, and adults. If left hemisphere specialization for reading occurs due to pre‐ existing HSF bias in the left hemisphere, than LH specialization for HSF information will be present before children have word‐reading ability, i.e., in the pre‐readers. In addition, children who demonstrate greater left than right lateralization for HSF may exhibit better word recognition ability. Adults show the predicted left hemisphere lateralization for HSF information and for words, but in pre‐readers, neither of these hemispheric biases is apparent. However, it is the case that in both children and adults, a higher left hemisphere bias for high spatial frequency visual information was correlated with a higher left hemisphere bias for words, indicating an early relationship between these two hemispheric biases.