, 2005). According to the LC/NE theory of the P3, these correlations result from a causal relationship: the NE impulse from the LC both causes

the synchronised depolarisation resulting in the scalp P3 as well as facilitating the behavioural response. Therefore, P3 and behaviour correlate on a single-trial level. Nieuwenhuis et al. (2005) propose that, following the decision about stimulus significance (categorisation Tyrosine Kinase Inhibitor Library research buy of the stimulus into a class of items requiring state transitions in light of the current strategy), an LC release of NE facilitates the selection of appropriate responses, regardless of the nature of the response (e.g. movements or memory updating). The P3’s RT-alignment also results from a causal relationship: NE from the LC facilitates state shifts and causes the P3. We thus focus on the LC/NE theory of the P3 here since this account is not only see more neurobiologically explicit, but also, of the current P3 theories, it is the one that most directly predicts response-alignment. In our view, the previous findings outlined in Section 1.2 are consistent with the P600 as a marker of subjective significance of linguistic material, rather than of structural processing. Here, we put this hypothesis to a critical test by investigating if

the late positivity following structurally deviant linguistic material (-)-p-Bromotetramisole Oxalate shows the RT-alignment typical of the P3, as predicted by the P600-as-LC/NE-P3 hypothesis. RT alignment is neither a necessary nor an obvious feature of theories assuming that the P600 reflects linguistic processing or other aspects of stimulus analysis. Post-hoc additions to such theories could explain RT alignment of the P600. However, as discussed in Section 1.1, the relationship between P3 latency and RT is reliable. A dissociation between P600 latency and RT would falsify critical predictions of the P600-as-P3 hypothesis. Previous research demonstrated RT alignment of the error-related negativity (Debener et al., 2005) and

multiple members of the P3 family (Makeig et al., 2004), and onset alignment of N100/P100 (Jung et al., 2001). Cummings et al. (2006) found that a stimulus-interpretative component, the N400 (Kutas & Federmeier, 2011), is aligned to stimulus onset, not RT, thereby establishing that late, high-level components can be stimulus aligned. Previous sentence processing experiments lack the required information for investigating RT alignment of components. Either no overt task was used, or the task was delayed relative to the critical stimulus. We are not aware of previous electrophysiological sentence processing studies in which participants judged linguistic deviancy as soon as they detected the error, allowing for a correlation of RT and P600 latency. The present study aimed to fill this gap.