Native-language N400 and P600 predict dissociable language-learning abilities in adults

Abstract

Language learning aptitude during adulthood varies markedly across individuals. An individual's native-language ability has been associated with success in learning a new language as an adult. However, little is known about how native-language processing affects learning success and what neural markers of native-language processing, if any, are related to success in learning. We therefore related variation in electrophysiology during native-language processing to success in learning a novel artificial language. Event-related potentials (ERPs) were recorded while native English speakers judged the acceptability of English sentences prior to learning an artificial language. There was a trend towards a double dissociation between native-language ERPs and their relationships to novel syntax and vocabulary learning. Individuals who exhibited a greater N400 effect when processing English semantics showed better future learning of the artificial language overall. The N400 effect was related to syntax learning via its specific relationship to vocabulary learning. In contrast, the P600 effect size when processing English syntax predicted future syntax learning but not vocabulary learning. These findings show that distinct neural signatures of native-language processing relate to dissociable abilities for learning novel semantic and syntactic information.

Keywords: Adult language learning; Event-related potential; Individual differences; N400; P600.

Fig. 1

Tasks and experimental design. (A) Participants completed a pre-training EEG session on Day 1 of the study, prior to training and testing on the miniature artificial language (MAL). Days 2 and 3 included MAL training and testing, and Day 4 included only MAL testing. The entire protocol spanned no more than six calendar days. (B) EEG was recorded while participants listened to English sentences and performed an acceptability judgment task. The unacceptable sentences contained either a semantic or a morphosyntactic violation. (C) On each MAL training trial, participants watched an animated clip, heard the pre-recorded sentence, and repeated it aloud. Each training sentence was presented 12 times over the course of three days. (D) Training was followed by a daily Vocabulary test. Participants heard a MAL word and had to select the corresponding picture. (E) Participants subsequently performed an auditory sentence acceptability judgment task in the MAL. The unacceptable sentences contained either a semantic or a morphosyntactic violation.

Fig. 2

Waveforms recorded in response to semantically acceptable and unacceptable sentences in English, with channel locations on the scalp indicated by white circles. Scalp plot shows the mean amplitude of the N400 effect over the 250–500-ms analysis window. Analysis window (250–500 ms) and all time points at which acceptable and unacceptable sentences differ significantly are indicated by bars on a representative channel, Cz.

Fig. 3

Waveforms recorded in response to syntactically acceptable and unacceptable sentences in English, with channel locations on the scalp indicated by white circles. Scalp plot shows the mean amplitude of the P600 effect over the 250–1000-ms analysis window. Two analysis windows (early P600: 250–500 ms; late P600: 500–1000 ms) and all time points at which acceptable and unacceptable sentences differ significantly are indicated by bars on a representative channel, Pz.

Fig. 4

Initial learning and attainment of the MAL. Vocabulary was measured by a forced-choice word-to-picture matching test (chance performance = 0.25). Semantic and syntactic knowledge were measured by sentence acceptability judgment (chance = 0.5). Each circle represents one participant.

Fig. 5

Structural models of the relations between native-language N400 magnitude and language learning aptitudes. Voc: Vocabulary Day 1; Sem: Semantics Day 1; Syn: Syntax Day 1; *: significant path coefficients (p < 0.050).

Fig. 6

Scatter plots between native-language ERPs and novel-language learning outcomes. (A) A larger N400 effect in response to semantic anomalies in English was associated with better Vocabulary learning on Day 1. (B) A larger early P600 effect in response to syntactic anomalies in English was associated with better Syntax learning on Day 1. Scalp distribution maps below the scatter plots depict four representative N400 and early P600 responses on both ends of the spectrum.

Fig. 7

Scatter plots reflecting individuals’ response dominance across early (250–500 ms, x-axes) and late (500–1000 ms, y-axes) time windows for (A) semantic processing and (B) syntactic processing of the native language. In (A), individuals in the bottom right quadrant show the canonical N400 to semantic anomalies. In (B), individuals in the top left quadrant show the canonical P600 to syntactic violations.