Lochy, A. | Search bioRxiv

bioRxiv2018

Teaching methods shape neural tuning to visual words in beginning readers

The impact of global vs. phonics teaching methods for reading on the emergence of left hemisphere neural specialization for word recognition is unknown in children. We tested 42 first graders behaviorally and with electroencephalography with Fast Periodic Visual Stimulation to measure selective neural responses to letter strings. Letter strings were inserted periodically (1/5) in pseudofonts in 40sec sequences displayed at 6Hz and were either words globally taught at school, eliciting visual whole-word form recognition (global method), or control words/pseudowords eliciting grapheme-phoneme mappings (phonic method). Selective responses (F/5, 1.2Hz) were left lateralized for control stimuli but bilateral for globally taught words, especially in poor readers. These results show that global method instruction induces activation in the right hemisphere, involved in holistic processing and visual object recognition, rather than in the specialized left hemisphere for reading. Poor readers, given their difficulties in automatizing grapheme-phoneme mappings, mostly rely on this alternative inadequate strategy.

neuroscience↗

bioRxiv2017

The Non-Linear Development Of The Right Hemispheric Specialization For Human Face Perception

The developmental origins of human adults right hemispheric specialization for face perception remain unclear. On the one hand, infant studies have generally shown a right hemispheric advantage for face perception. On the other hand, the adult right hemispheric lateralization for face perception is thought to slowly emerge during childhood, due to reading acquisition, which increases left lateralized posterior responses to competing written material (i.e., visual letters and words). Since methodological approaches used in infant and children usually differ, resolving this issue has been difficult. Here we tested 5-year-old preschoolers varying in their level of visual letter knowledge with the same fast periodic visual stimulation (FPVS) paradigm leading to strongly right lateralized electrophysiological occipito-temporal face-selective responses in 4- to 6-month-old infants (de Heering & Rossion, 2015). Childrens face-selective response was much larger and more complex than in infants, but did not differ across hemispheres. However, there was a small positive correlation between preschoolers letter knowledge and their right hemispheric specialization for faces. These observations suggest that several factors contribute to the adult right hemispheric lateralization for faces, and point to the value of FPVS coupled with electroencephalography to assess specialized face perception processes throughout development with the same methodology.

neuroscience↗