Fig 3. P300 averages from subject 10.

While looking at a chequerboard that inverted every second, the subject was presented with oddball stimuli every 7sec-13sec with a random pattern. The recording was 5 minutes long. A: the event-triggered average from the inner electrode d[n], B: the event-triggered average from the output e[n] of the DNF, C: the output from the LMS filter (adaptive FIR filter) and D: from the Laplace filter: $\tilde{d}\left[n\right]-\tilde{x}\left[n\right]$ with DC and 50 Hz removed after the subtraction operation.