Learning to use words: event-related potentials index single-shot contextual word learning

Abstract

Humans have the remarkable capacity to learn words from a single instance. The goal of this study was to examine the impact of initial learning context on the understanding of novel word usage using event-related brain potentials. Participants saw known and unknown words in strongly or weakly constraining sentence contexts. After each sentence context, word usage knowledge was assessed via plausibility ratings of these words as the objects of transitive verbs. Plausibility effects were observed in the N400 component to the verb only when the upcoming novel word object had initially appeared in a strongly constraining context. These results demonstrate that rapid word learning is modulated by contextual constraint and reveal a rapid mental process that is sensitive to novel word usage.

Figure 1

Schematic of electrode placement

Figure 2

ERPs to Known and Unknown target words in Context sentences at midline electrode sites. Analyses over a restricted and a complete set of electrode sites indicate that sentential context did not modulate N400s for Unknown targets; N400 amplitudes were smallest for Known words in High constraint contexts. Additional distributional analyses indicated that N400 differences between High/Known and all other conditions were largest medially.

Figure 3

Plausibility effect for Verbs preceding Known and Unknown targets. ERPs at right-medial central electrode (RMCe) are plotted for plausible and implausible verbs in each condition.

Figure 4

Plausibility effect for Known and Unknown targets. Event-related potentials at right-medial central electrode (RMCe) are plotted for Known and Unknown targets preceded by plausible and implausible verbs. Unlike their preceding verbs, no significant plausibility effects were observed for Known and Unknown word targets in N400 or LPC component timewindows.

Figure 5

Grand average ERPs to test sentences in their entirety across all participants. N400 effects are evident for each sentence item sequentially: at 400 ms for the pronoun, 800ms for the verb, 1200ms for the article, and 1600ms for the final test noun.

Figure 6

Example of grand average ERPs to test sentences where participants show two different patterns: 1) plausibility effects at the verb only (in High/Known only), and 2) continuing effects across the sentence. Like in Figure 5, N400 effects are shown for each sentence item sequentially, beginning with the pronoun at 400ms.