We also examined the associations between the FH measures and the parietal P3 amplitude to target stimuli measured using the visual oddball paradigm. The visual oddball paradigm has been previously described (Cohen et al., 1994). Briefly, three types of visual stimuli are presented: target (the letter X), non-target (squares), and novel (a different colored geometric figure) on each trial. Subjects are required to respond to the target stimulus by pressing a button as quickly as possible, but not at the expense of accuracy. A total of 35 target stimuli, 210 non-target stimuli, and 35 novel stimuli trials were presented with the probabilities of occurrence of the trials being 12.5% for the target trials, 75% for non-target trials and 12.5% for novel trials. Trials with baseline corrected amplitudes greater than 75 μV were marked as artifact contaminated and not analyzed further. Subjects whose data did not contain a minimum of 20 artifact-free trials in each condition were not selected for analysis. The P3 amplitude used in this analysis was the peak amplitude to target at the midline parietal (Pz) electrode between 300–700 milliseconds after stimulus presentation.
