The visual P3 (VP3) amplitude was measured as the voltage difference between the prestimulus baseline and the largest positive going peak in the latency window 300–600 ms after stimulus onset. For each individual, the amplitude and latency measures were calculated using a semi-automatic peak-picking program, wherein the time window for each component was manually selected in the computer while the peak within the window was automatically detected, measured, and tabulated for each channel. However, operator intervention was possible during the process to ensure that the computer did not make anomalous peak selections. Each subject had a minimum of 20 good trials in each condition. The grand averages were computed and plotted to determine the components and time windows (Kamarajan et al., 2005).
