Behavioral-Based Sorting of Single-Trial EEG Data Reveals Evidence for ERP Correlates of Facilitation and Interference in the Picture-Word Interference Task.

A paradigm that has been widely used in cognitive science to examine questions about language production has produced an as-yet-unresolved conundrum in the findings of several event-related potential (ERP) studies. Using the picture-word interference (PWI) task, these studies have found behavioral evidence of interference effects (i.e., slower and/or less accurate responses) but ERP evidence of typical priming (i.e., smaller N400s) when to-be-named pictures are presented with semantically related words. To address these seemingly contradictory results, we performed a semantic PWI experiment with two modifications from the typical design. First, we implemented a novel behavior-contingent analysis of semantically related word-picture pairs in which single-trial ERP data were reaveraged for word-picture pairs that either showed a facilitation pattern or an inhibition pattern (faster or slower RTs for related than unrelated pairs). Second, we extended the ERP analysis epoch to latencies not typically analyzed in previous studies due to concerns about speech artifact. In the behavioral contingent averaged ERPs, the "facilitation bins" produced typical priming in early (200-400 ms) and late (400-600 ms) N400 epochs, while the "inhibition bins" produced reversed priming (greater negativity for related than unrelated prime words) in the late N400 epoch. In addition, after correcting for speech artifact, we observed reversed priming for the semantic condition in a later epoch (700-1200 ms). Together, these results help resolve the apparent conflict between neural and behavioral responses in the PWI paradigm and suggest a way forward in using response-contingent averaging of ERP data in language production.