Figure 4.

ERPs from monkey Y showing the ERN and Pe when errors are committed in the saccadic stop-signal task with the same conventions as in Figure 2. Response aligned ERPs from correct no-stop trials and errant noncanceled trials are displayed for multiple electrode locations. On error trials, a significant negativity can be observed on electrodes FCz and F3, and a later negativity can also be observed on electrode Pz. Following this, a significant positivity can be observed on the majority of electrodes. This positivity is earliest and highest in amplitude at frontal medial electrode sites.