ERP traces and scalp maps of responses.

<p>Group average ERPs +/− sem envelope for YNs (top), ONs (middle), and ADs (bottom). A. Responses to target words presented alone (black), include P1, N2, N2b and P3 components. The amplitude of the N2 and P3 components increases with the addition of a task irrelevant flow stimulus superimposed on the word stimulus (blue). The N2 decreases, and the N2b and P3 are eliminated, when the superimposed flow and word stimuli are presented in the context of task change to the flow task (red). Voltage scalp maps (center) with prominent occipital/posterior activation of the N2 response to the word alone stimuli. B. ERPs target optic flow presented alone include N2, N2b and P3 (black) with the P3 increased by adding an irrelevant word stimulus (red). The N2b and P3 are eliminated when switching to the word task (blue). Voltage scalp maps (center) show prominent parietal/posterior activation of the optic flow N2. C. ERPs to non-target words presented alone (black) and the effect of adding an irrelevant motion stimulus (blue) or switching tasks (red). D. ERPs to non-target flow presented alone (black) and the effect of adding an irrelevant word stimulus (red) or switching tasks (blue). The non-target responses after 700 ms illustrate subtler effects of the transition to the masking noise stimulus.