The Fixation and Saccade P3 Figure 6. Direct comparison of fixation distracter and saccade distracter EPs. Same as Figure 5 but for distracters rather than targets. doi:10.1371/journal.pone.0048761.g006 of the P3 between fixation and saccade trials was not significant across subjects (paired t-test; t(6) = 21.01, p = 0.35, two tailed). P3 signal strength was also quantified for each subject by first expressing the mean TMD positivity at each time point and electrode as a t-statistic. Similar to the measure of P3 amplitude described above, at every time point at which there was a significant P3, the mean P3 amplitude was calculated over only those electrodes that exhibited a significant P3 difference at each time point. The signal strength was defined as the mean t-statistic as observed over all of the significant time points. The P3 signal strength did not differ significantly between the saccade and fixation conditions across subjects (mean P3 amplitude expressed as a t-statistic in fixation trials: 2.660.1; mean amplitude measure expressed as t-statistic in saccade trials: 2.560.1; t(6) = 0.85, p = 0.43, two-tailed). Testing P3 Parameters for Dependence on the Difference in Image Presentation Time All parameters of the saccadic and fixation P3 that were compared across the two conditions were tested for correlations with the difference in image presentation time observed between the two conditions (see Behavioral results). Recall that, on average across subjects, the difference image presentation time between saccade and fixation conditions was minimized to be 2766 ms. Differences in image presentation time between the fixation and saccade conditions for each of the 7 subjects with significant PLOS ONE | www.plosone.org 10 November 2012 | Volume 7 | Issue 11 | e48761