Predictability effects in the processing of negation: an ERP study

To examine whether processing of negated meanings is facilitated in highly predictable contexts and proceeds incrementally rather than with a delay, we asked participants to read highly constraining sentences containing negated adjectives (e.g., awake/responding/commercial) that were either strongly expected in a high-cloze condition (awake), weakly expected in a low-cloze condition (responding), or contextually inappropriate in a semantic violation condition (commercial). In accordance with findings for affirmative sentences, a smaller N400 was elicited for the high-cloze condition than for the low-cloze one, and for the low-cloze condition than the violation condition. The smaller N400 for the high-cloze condition suggests facilitated processing for strongly expected continuations. Furthermore, in the post-N400 time-windows, two distinct post-N400 positivities (PNPs) were elicited for the two weakly expected and unexpected continuations compared to strongly expected continuations. Firstly, a larger anterior PNP was observed for weakly expecting, but plausible, continuations in the low-cloze condition, suggesting inhibitory processes suppressing initial predictions to allow for the integration of the new information. Secondly, a larger posterior PNP was observed for unexpected and implausible, continuations in the violation condition, indexing contextual integration difficulties. Together, these findings suggest that negation can be processed incrementally in highly constraining contexts where predictions can be made, engaging similar neural mechanisms as predictive processing in affirmative sentences in such contexts. In sum, our results are consistent with previous ERP research on prediction processing in both affirmative and negated contexts but inconsistent with previous research using behavioral methods.