To investigate how co-speech gestures modulate linguistic understanding, we conducted an EEG experiment exploring the amplitude changes in the N400 component. We used videos of a person uttering underspecified action sentences which either featured no gesture or an iconic co-speech gesture that represented a more specific action. The following target sentence contained an instrument noun followed by its required action verb; these could either match the action represented in the previously seen gesture or mismatch it. We measured ERPs for both the nouns and the verbs and found an N400 effect for mismatching target words as well as a sustained positivity effect for both gesture conditions.

We employ a scenario-sentence-verification paradigm to inves-tigate the role of scenario-given alternatives for the process-ing of affirmative and negative sentences. We show that forboth affirmative and negative sentences the N400 amplitude islarger if the context model provides multiple alternatives fora true sentence continuation relative to the case when it pro-vides only a unique referent. Additionally, we observe a latepositivity effect for negative relative to affirmative sentences,independent of the context model.

Bare numerals (e.g. two) seem to be ambiguous between two readings: the exactly and the at least reading. We present an ERP study that explores this issue. We show that the pattern of the ERPs elicited by critical nouns in sentences with unembedded bare numerals depends on the participant’s choice of the reading of the numeral. For those responders who consistently apply the exactly reading in their truth-value judgement, sentences that are true only under the at least reading are associated with a sustained negativity effect compared to sentences that are true also under the exactly reading. However, no such effect is evident for the responders who apply the at least interpretation. We argue that this result falsifies the exactly-theory of numerals and speaks in favor of the ambiguity account.