Grand average event-related potentials.

<p>Here, <i>n</i>=5 for each session in the Single-trial group (participant 8 excluded) and <i>n</i>=4 for each session in the Triple-trial group (participants 10 and 12 excluded). O* denotes an average of four occipital channels (PO7, PO8, O1 and O2). Zero time corresponds to the beginning of the stimulus. Waveforms are presented in black for the 1st session and in dark, medium and light gray for sessions 2, 3 and 4, respectively.