Figure 3. ERP significant clusters.

For all three rows, the left panel shows the sum of t-values for the entire cluster at each time point, giving a measure of the temporal evolution of the cluster as a whole. In keeping with the ERP convention used for the waveforms, negativity is plotted upwards. The middle panel is a topographic map of the voltage difference between the two conditions (or sets of conditions), integrated over the time range indicated. The Right panel is the ERP timelocked to a within-trial trigger, shown at a single representative channel, as indicated. The trigger point to which the response is timelocked is indicated (see figure 1 for trigger locations). A: N400 effect timelocked to very beginning of the sentence. This response is evoked by the inanimate subjects of the ISO sentences (e.g. The car vs. the boy). B: P600-like posterior positivity evoked by reversible vs. irreversible sentences, occurring approximately at the border between the second and third sentence segments. For relative-clause containing sentences (SS and SO), the timelocking point is the onset of the first word following the relative clause, e.g. “The woman who the man is teaching IS very tired right now.” C: Left anterior negativity evoked by reversible vs. irreversible sentences during the post-sentence memory delay, prior to picture onset.