Figure 3

Event-related oscillations for all the electrodes.The upper part presents the event-related oscillations (EROs) time-frequency chart for Targets on the left (X-mark), and rare distractors (Novels) on the right ("no-smoking" symbol). It is shown for the 24- to 44-Hz band, and between -320 to 600 ms, summing up all 9 electrodes for all the subjects. The color scale represents the relative amount of power in standard deviation (reference period from -320 to 0 ms). This illustrates that the 32- to 38-Hz EROs in response to Targets are quite low in response to Novels. It thus does not come as a surprise that the statistical comparison of Target-related vs. Novel-related power for all electrodes is significant (lower time-frequency chart). Cold colors code for a trend towards greater power in the Novel condition, whereas hot colors represent greater power level in the Target condition. The scale represents the cumulative p distribution stated in percent. Regions above the .05 and .01 threshold are contoured in black. The numbers 1, 5, 95 and 99 represent the cumulative p value in percent, respectively equivalent to.01, .05 for Novels and .05, .01 for Targets. The solid and dotted black lines correspond to the response time and standard deviation, respectively. The result table provides the statistics for the time interval from 200 to 500 ms, and from 24 to 44 Hz, using a threshold p ≤ 0.01. Volume and time-frequency cluster p values are given corrected for multiple comparisons. Note that the ensemble statistics represent the probability to have the given amount of time-frequency points above the threshold (12 over 165 time-frequency points), and not the number of clusters as in EPs or fMRI. At the same threshold, there were no significantly larger power emissions in the Novel than in the Target condition (not even at the .05 threshold).