Impact of foreknowledge of stimulus-effector (S-E) mapping on abstract and effector-selective signatures of evidence accumulation in the human brain. B, D, Error bars indicate SEM across subjects. Color bar represents signal amplitude. The colored vertical lines indicate mean RT for each condition. A, Grand average signal topography of the difference between trials on which participants responded with a left versus right button click (collapsing across the three S-E mapping conditions) across a window of −200 to 0 ms centered on response execution. B, β-band lateralization traces (8–16 and 18–30 Hz) measured as the average difference in amplitude over motor regions contralateral minus ipsilateral to the responding hand, aligned to coherent motion onset (left), cue (middle), and response execution (right). Markers running along the bottom of the plot indicate the time points at which the lateralized β-band traces deviated significantly from zero (p < 0.05); a significant and sustained lateralization with respect to the hand of eventual response was only observed across the decision timeframe when the decision-reporting effector was known in advance. C, Grand-average signal scalp topography of the Fixed and Varied S-E mapping conditions across a time window of 400 to 550 ms centered on target onset. D, CPP waveforms aligned to the onset of coherent motion (left), cue (middle), and response execution (right). E, Single-trial CPP surface plot sorted from the earliest to latest CPP peak latencies (curved black line; right) in the two motion discrimination conditions shows that the CPP did not remain at an elevated level after decision but descended toward baseline levels upon reaching its peak. Although there was considerable variability in the time at which the CPP reached its peak, it consistently returned to baseline levels shortly afterward. Although the abstract and effector-selective signals appear to accumulate sensory evidence in a similar way, they are dissociable in terms of their post-decision dynamics.