Electrophysiological markers of orthographic pattern learning in school-aged children with reading challenges: An ERP investigation.

BACKGROUND: Previous studies suggested that children with reading difficulty have impaired statistical learning ability in extracting distributional orthographic regularities. However, the neural mechanisms underlying have not been fully investigated. AIMS: The current study aimed to identify the electrophysiological markers and to examine the neural underpinnings of statistical learning of orthographic regularities in children with reading difficulties. METHODS AND PROCEDURES: Using the event-related potentials (ERPs) and the orthographic learning task, 157 children were exposed to a sequence of artificial pseudocharacters with varying levels of positional and semantic consistency (low at 60 %, moderate at 80 %, and high at 100 %). OUTCOMES AND RESULTS: Poor readers elicited an increased N170 response in the low consistency and a lack of left-lateralized P300 effect when learning positional regularities of radicals. Similarly, larger N170 effects were observed in poor readers, while similar N400 effects were found in both poor and average readers when learning semantic regularities of radicals. CONCLUSIONS AND IMPLICATIONS: Our findings indicate that poor readers may have trouble using statistical information for early-stage orthographic pattern extraction, yet they can identify semantic inconsistencies after sufficient exposure. These results deepen our understanding of the neural mechanisms involved in statistical learning for poor readers and aid in improving criteria for differentiating between typically developing children and those with reading challenges.

Multiple mechanisms regulate statistical learning of orthographic regularities in school-age children: Neurophysiological evidence.

Using event-related potentials (ERPs), this study investigated how the brains of Chinese children of different ages extract and encode relational patterns contained in orthographic input. Ninety-nine Chinese children in Grades 1-3 performed an artificial orthography statistical learning task that comprised logographic components embedded in characters with high (100%), moderate (80%), and low (60%) positional consistency. The behavioral results indicated that across grades, participants more accurately recognized characters with high rather than low consistency. The neurophysiological results revealed that in each grade, the amplitude of some ERP components differed, with a larger P1 effect in the high consistency condition and a larger N170 and left-lateralized P300 effect in the low consistency condition. A smaller N170 effect occurred in Grade 3 than in Grade 1, and a larger P300 effect occurred in Grade 1 than in either Grade 2 or 3. These findings suggest the dynamic nature of statistical learning by showing that neural adaptation associated with N170, and attention and working memory related to P1 and P300, regulate different types of structural input, and that children's abilities to prioritize these mechanisms vary with context and age.

Processing Ambiguous Morphemes in Chinese Compound Word Recognition: Behavioral and ERP Evidence.

This study examined the processing of ambiguous morphemes in Chinese word recognition with a masked priming lexical decision task. Both behavioral and event-related potential (ERP) were recorded. All targets were bimorphemic compound words that contained ambiguous morphemes as the first morphemes. The ambiguous morphemes either took the dominant or subordinate interpretation, depending on the second morphemes. The prime words contained the same ambiguous morphemes in the dominant interpretation, the subordinate interpretation, or were unrelated to the targets. Analyses on response times revealed significant facilitative priming whenever primes and targets shared morphemes, but the strength of facilitation was stronger when the morpheme meanings were consistent. A similar pattern was found in the analyses of N400 (300-500 ms after target onset) amplitudes. However, in the earlier N250 time window (200-300 ms after target onset), only the dominant targets, but not the subordinate ones, were primed by the morpheme-sharing primes. More importantly, the strength of facilitation was similar between the dominant and subordinate primes. These results have two implications to the processing of ambiguous morphemes during Chinese compound word recognition. First, the morpheme meanings could be activated rapidly. Second, the more frequently used dominant meanings could be activated more easily than the less frequently used subordinate meanings.