The N400 effect in elementary school children with reading difficulties

• In Event: Academic and Behavioral Outcomes Among Children with Developmental Disabilities

Abstract

The present study uniquely examined the N400 lexicality effect as a potential biomarker for reading difficulties in elementary school children. The N400 component is a waveform captured by electroencephalography (EEG) when individuals engage in meaning-processing tasks (Kutas & Hillyard, 1980). The N400 lexicality effect refers to a systematic difference in N400 amplitudes elicited by words that follow orthographic-phonological regularities and words that do not (Tzeng et al., 2017). It tends to be present in proficient readers but not beginning readers (Araújo et al., 2012). However, it has scarcely been studied in children with reading difficulties, a prevalent learning difficulty (Shaywitz et al., 2021).

Fifty-two children aged 7 to 10 participated in the present study; 21 of them were reported to have reading difficulties by their parents. Children completed standardized measures of decoding fluency, sight word fluency, receptive vocabulary, and reading comprehension. Children also completed the N400 task during which continuous EEG was recorded using a 128-site Geodesic Sensor Net. In the N400 task, children viewed 114 real words, 114 nonwords (made-up words that violate the orthographic-phonological regularities of English), and 20 animal words which acted as catch trials (Coch, 2015). Words came in three difficulty levels (grades K-1, 2-3, and 4-5).

First, we hypothesized the N400 effect to be present in children with typical reading skills but not children with reading difficulties. ANOVA showed that typical readers showed a stronger N400 effect defined as the difference between N400 amplitudes elicited by real words and nonwords (M= 1.27, SD= 1.54) than children with reading difficulties (M= -0.16, SD= 2.06), F(1, 46) = 7.51, p= 0.0087. Children with typical reading skills may have stronger orthographic-phonological regularity knowledge or stronger connections between orthographic, phonological, and semantic processing. Their meaning processing shown by N400 systematically differed by lexicality.

Second, we hypothesized that word difficulty level would moderate the N400 amplitude for children with reading difficulties but not typical readers. A repeated measure ANOVA showed that the interaction between group and word type was significant [F(1, 46) = 5.79, p= 0.0203, partial Eta squared = .11] and the main effect of word type was significant ([F(1,46)= 8.14, p= 0.0065, partial Eta squared = .15]. Amongst real words, word difficulty level did not modulate N400 amplitudes for either group of children. Amongst nonwords, word difficulty level modulated the N400 amplitudes for typically developing children but not children with reading difficulties. Nonword distance (the distance between a reader’s representation of a nonword and the existing words in the reader’s mental lexicon) may explain why the “difficulty level” of nonwords could modulate meaning processing (Norris, 2006)

Third, we explored the associations between language-literacy skills and N400. Correlation analyses indicated that the N400 effect was significantly correlated with sight word reading fluency. Theories of N400 were drawn to understand the current state of mixed findings regarding the relationships between N400 and language-literacy skills. Instead of mapping on to a specific stage in reading theories, N400 better represents an interactive, dynamic system supporting meaning processing (Lau et al., 2008).

Authors

• Linda Sun, Syracuse University
  Presenting Author

• Sadie Pazoki, Texas A&M University

• Qinxin Shi, University of Utah

• Steven Woltering, Texas A&M University