Neural Signatures of ACE Figure 4. ERPs from motor responses. A) Compatibility effects and difference waveforms for MP and RAP. B) Voltage maps from compatible and incompatible categories in the 2100, 0 and 200 ms. C) Selected electrodes (Cz) showing compatibility effects in OHG and CHG. Channel locations are shown in the grey circle inside the figure. doi:10.1371/journal.pone.0011751.g004 Overall results The shorter latency of reaction times for the compatible condition is indicative of the action that was effectively facilitated by the sentence, inducing a quicker and more precise movement. This was confirmed cortically as larger amplitudes of MP associated with central motor speed and the control of force [65,68] that occurred with the action-sentence compatibility. As addressed below, this facilitation effect also had a corresponding cortical effect with a larger RAP on action-sentence match, suggesting an enhancement of bottom-up attentional resources that in turn facilitated quickness and response precision. Regarding the relationship between the behavioral data and ERP in the neutral condition, we found an N400-like effect, similar to that in the compatible condition and shorter RTs for NS. NS presented no difficulties for semantic integration of action because no neural substrates are shared between the sentence and action in a compatible/incompatible manner in this condition. Moreover, as detailed in the Materials and Methods section, the NS list involved more predictable sentence endings than the other two lists. Consequently, this should explain the shorter RTs for NS. The predictability modulated the RTs and N400 because predictability facilitates the expectation of semantic integration [75,79–82]. Then, both predictability and compatibility are different effects of facilitation that account for the balance between conditions. Semantic Effects The negativity elicited by incompatible stimuli in both OHG and CHG resembles the N400 component usually observed for PLoS ONE | www.plosone.org 8 July 2010 | Volume 5 | Issue 7 | e11751