Semantic processing in children 0 to 6 years of age: an N400 analysis

Understanding words in context: A naturalistic EEG study of children's lexical processing

When listening to speech, adults rely on context to anticipate upcoming words. Evidence for this comes from studies demonstrating that the N400, an event-related potential (ERP) that indexes ease of lexical-semantic processing, is influenced by the predictability of a word in context. We know far less about the role of context in children's speech comprehension. The present study explored lexical processing in adults and 5-10-year-old children as they listened to a story. ERPs time-locked to the onset of every word were recorded. Each content word was coded for frequency, semantic association, and predictability. In both children and adults, N400s reflect word predictability, even when controlling for frequency and semantic association. These findings suggest that both adults and children use top-down constraints from context to anticipate upcoming words when listening to stories.

The Neural Underpinnings of Processing Newly Taught Semantic Information: The Role of Retrieval Practice

Purpose Recent behavioral studies have demonstrated the effectiveness of implementing retrieval practice into learning tasks for children. Such approaches have revealed that repeated spaced retrieval (RSR) is particularly effective in promoting children's learning of word form and meaning information. This study further examines how retrieval practice enhances learning of word meaning information at the behavioral and neural levels. Method Twenty typically developing preschool children were taught novel words using an RSR learning schedule for some words and an immediate retrieval (IR) learning schedule for other words. In addition to the label, children were taught two arbitrary semantic features for each item. Following the teaching phase, children's learning was tested using recall tests. In addition, during the 1-week follow-up, children were presented with pictures and an auditory sentence that correctly labeled the item but stated correct or incorrect semantic information. Event-related brain potentials (ERPs) were time locked to the onset of the words noting the semantic feature. Children provided verbal judgments of whether the semantic feature was correctly paired with the item. Results Children recalled more labels and semantic features for items that had been taught in the RSR learning schedule relative to the IR learning schedule. ERPs also differentiated the learning schedules. Mismatching label-meaning pairings elicited an N400 and late positive component (LPC) for both learning conditions; however, mismatching RSR pairs elicited an N400 with an earlier onset and an LPC with a longer duration, relative to IR mismatching label-meaning pairings. These ERP timing differences indicated that the children were more efficient in processing words that were taught in the RSR schedule relative to the IR learning schedule. Conclusions Spaced retrieval practice promotes learning of both word form and meaning information. The findings lay the necessary groundwork for better understanding of processing newly learned semantic information in preschool children. Supplemental Material https://doi.org/10.23641/asha.15063060.

Semantic word integration in children with cochlear implants: Electrophysiological evidence

Differential auditory experiences of children with hearing-loss who receive cochlear implants (CIs) may influence the integration of lexical and conceptual information. Here we measured event-related potentials during a word-picture priming task in CI-using children (n = 29, mean age = 81 months) and typically-hearing children (n = 19, mean age = 75 months) while they viewed audiovisual-word primes and picture targets that were semantically congruent or incongruent. In both groups, semantic relatedness modulated ERP amplitude 300-500ms after picture onset, signifying an N400 semantic effect. Critically, the CI-using children's responses to unrelated pairs were significantly more negative than hearing children's responses. Group differences were mirrored in an earlier 150-275ms time window associated with a P2 response. The present findings suggest attentional and/or strategic differences impact semantic processing and contribute to the N400 differences observed between groups.