Individual differences in subcomponents of the N400: Comprehension ability predicts contextual support effects while spelling ability predicts orthographic anomaly effects.

The N400 ERP component has been characterized as a response reflecting binding of semantic memory states to create a "multimodal conceptual representation" (Kutas & Federmeier, 2011). An assumption of this characterization is that the measured response itself reflects the synchronization of various neural processes required for language comprehension. Less is known, however, about how these processes vary across individuals and how specific language skills may modulate particular underlying subcomponents of the N400. In the current study, we measured the N400 response to words that were (1) unexpected (i.e., low cloze in low constraint) or (2) orthographically related (OR) anomalies compared with expected words (i.e., high cloze in high constraint), and we investigated how these effects were related to participants' reading comprehension ability, vocabulary, and spelling ability. We found that contextual support N400 effects were larger for individuals with superior reading comprehension skills, whereas OR anomaly N400 effects were larger for individuals with superior spelling ability. These findings support the characterization of the N400 as a composite of various comprehension-related neural processes. The current study demonstrates that individual differentiation in the strength of these skills is differentially associated with the N400 subcomponents related to contextual facilitation and orthographic processing. Reading comprehension ability is associated with stronger contextual support effects, which may reflect more effective use of contextual support in facilitating semantic retrieval. Spelling skill is more strongly associated with OR anomaly effects (in contexts supporting an orthographic neighbor of the presented anomalous word), which may reflect more precise word identification.