The effect of structure on context-driven word production: an EEG study

In context-driven picture naming studies, pictures are named faster following constraining (e.g., "The leaves fall from the”, picture: TREE) relative to nonconstraining (e.g., “The family played by the”, picture: TREE) sentences, indicating that word planning starts prior to target picture onset. Power decreases in the electroencephalogram in the alpha-beta band are consistently found prior to picture onset, suggesting they could reflect conceptual and lexical retrieval. However, this effect disappears in nonverbal contexts, which provide semantic information but lack structural composition. The present electroencephalography study aimed at investigating the behavioral and neural effect of syntactic structure on context-driven word production. Participants performed context-driven picture naming, where contexts were manipulated for structure (structured vs. unstructured, e.g., “leaves–fall–from” vs “larva–caterpillar–cocoon”) and context constraint (constraining vs. nonconstraining, as above). Pictures were named faster in constraining relative to nonconstraining contexts in both structured and unstructured conditions. Interestingly, structure in itself showed no behavioral facilitation in either constraint condition. The neural findings revealed a contrasting pattern. Power decreases in the alpha-beta band were observed following structured constraining compared to nonconstraining contexts, replicating previous findings, but this pattern was absent in the unstructured condition. We suggest that the presence of structure enables the selection of the activated morpho-syntactic features needed for the word’s syntactic integration with the sentential context before the target picture appears. The electrophysiological findings suggest that alpha-beta power decreases reflect concept and lemma retrieval as well as the selection of the relevant morpho-syntactic properties that receive activation from the lemma.