When temporal terms belie conceptual order.

We conceive of time as a sequential order of real-world events, one event following another from past to present to future. This conception colours the way we speak of time ("we look forward to the time") and, as we show here, the way we process written statements referring to the temporal order of events, in real time. Terms such as 'before' and 'after' give us the linguistic freedom to express a series of events (real or imaginary) in any order. However, sentences that present events out of chronological order require additional discourse-level computation. Here we examine how and when these computations are carried out by contrasting brain potentials across two sentence types that differ only in their initial word ('After' X, Y versus 'Before' X, Y). At sites on the left frontal scalp, the responses to 'before' and 'after' sentences diverge within 300 ms; the size of this difference increases over the course of the sentences and is correlated with individual working-memory spans. Thus, we show that there are immediate and lasting consequences for neural processing of the discourse implications of a single word on sentence comprehension.