In the initial phase of the study (Study 1) electrocortical arousal (EEG alpha activity) was assessed at four standardized sites (T3, T4, 01, and 02) from male and female (N = 17) international-caliber marksmen during rifle shooting performance. The task consisted of the execution of 40 shots at a conventional indoor target from the standing position. During each shot preparation, a significant increase in left temporal and occipital alpha activity was demonstrated, while the right hemispheric activity remained constant. Hemispheric laterality ratios (T4:T3) evidenced a significant shift toward right-brain dominance as the time to trigger pull approached. In the second phase of the study (Study 2) male and female (N = 15) marksmen performed the same shooting task and, additionally, the resultant EEG performance patterns were contrasted to those observed during the mental processing of sterotyped left-brain and right-brain mental tasks. Observed EEG patterns, that is, temporal ratios, during shooting replicated the results of Study 1, and furthermore, indicated that the laterality indices derived during shooting exhibited a more pronounced shift to right-brain processing than did those derived during right-brain mental task performance. The EEG data obtained during the comparative mental task states were used to interpret the shooting performance EEG findings in terms of the implications from bilateral or split-brain cognitive process theory.