Fig. 4.

Response-locked ERP waveforms depicting the ERN component, (averaged across FCz and Cz electrodes). Top panels: correct and error trials superimposed in each graph for each of the four musical practice levels (no, low, intermediate, and high). Bottom panels: response-locked difference waves (error minus correct trials) with the four musical practice levels superimposed (bottom left), and the corresponding topographic voltage map for the ERN component using the difference waveforms averaged across musical practice level (bottom right).