Development of the N400 for Word Learning in the First 2 Years of Life: A Systematic Review

Abstract

The N400 ERP component is a direct neural index of word meaning. Studies show that the N400 component is already present in early infancy, albeit often delayed. Many researchers capitalize on this finding, using the N400 component to better understand how early language acquisition unfolds. However, variability in how researchers quantify the N400 makes it difficult to set clear predictions or build theory. Not much is known about how the N400 component develops in the first 2 years of life in terms of its latency and topographical distributions, nor do we know how task parameters affect its appearance. In the current paper we carry out a systematic review, comparing over 30 studies that report the N400 component as a proxy of semantic processing elicited in infants between 0 and 24 months old who listened to linguistic stimuli. Our main finding is that there is large heterogeneity across semantic-priming studies in reported characteristics of the N400, both with respect to latency and to distributions. With age, the onset of the N400 insignificantly decreases, while its offset slightly increases. We also examined whether the N400 appears different for recently-acquired novel words vs. existing words: both situations reveal heterogeneity across studies. Finally, we inspected whether the N400 was modulated differently with studies using a between-subject design. In infants with more proficient language skills the N400 was more often present or showed itself here with earlier latency, compared to their peers; but no consistent patterns were observed for distribution characteristics of the N400. One limitation of the current review is that we compared studies that widely differed in choice of EEG recordings, pre-processing steps and quantification of the N400, all of which could affect the characteristics of the infant N400. The field is still missing research that systematically tests development of the N400 using the same paradigm across infancy.

Learning Words While Listening to Syllables: Electrophysiological Correlates of Statistical Learning in Children and Adults

“…Developmental changes were indexed generally by a reduction of amplitude and latency in the N100 ( Albrecht et al, 2000 ; Pang and Taylor, 2000 ). Similarly, N400 was found reduced in adults, as well as other differences in latency and duration of the wave (for a recent systematic review, see Junge et al, 2021 ).…”

“…Based on the reviewed literature, we expected that if the processes underlying aSL with linguistic materials were early maturing and stable across development, as previous behavioral works suggest (e.g., Saffran et al, 1997;Raviv and Arnon, 2018;Shufaniya and Arnon, 2018), no differences should be observed in the electrophysiological correlates indexing SL in the brain, like the N100 and the N400 ERP components, even though slight differences might be observed due to differences in topography, amplitude, and latency arising from development and maturation factors (Albrecht et al, 2000;Pang and Taylor, 2000;Junge et al, 2021). In contrast, if aSL with linguistic materials elicited different neural responses in children and adults, as previous studies conducted either with adults or children suggest (e.g., Cunillera et al, 2006Cunillera et al, , 2009Abla et al, 2008;Bosseler et al, 2016;Mandikal-Vasuki et al, 2017a,b;Choi et al, 2020;Soares et al, 2020;Pierce et al, 2021), distinct modulations in the N100 and the N400 components should be observed.…”

Age‐related differences in expectation‐based novel word learning

“…Unlike adult studies, which focus on word prediction during sentence comprehension (as well as semantic priming), N400 investigations of language processing during early childhood have mostly been restricted to semantic priming paradigms or word‐picture matching tasks (Junge et al, 2021). Semantic priming refers to the facilitation of target processing (for example, of the word pear ) following the presentation of semantically related prime words (such as apple ).…”

Studying the Developing Brain in Real-World Contexts: Moving From Castles in the Air to Castles on the Ground

“…In the real world, though, individual pictures rarely if ever flash on and off out of the darkness, and specific sequences of events virtually never reoccur. Similarly, in studies examining language acquisition, auditory evoked potentials tend to be measured relative to the presentation of individual nouns or sentences ( Junge et al, 2021 ), whereas real-world language comprehension critically requires parsing single words out of a complex, dynamic speech stream.…”