Variable Attentional Control (VAC) task. The task is aimed to assess the effects of an increasing demand in attention. There were three levels of attention: (1) low level (LOW), when all three sizes of arrows were congruent in direction with each other, and subjects were cued to attend to the big arrow; (2) intermediate level (INT), when the big arrow was incongruent in direction to the small and the medium arrows, and subjects were cued to attend to either big or small arrows; and (3) high level (HIGH), when the medium arrows were incongruent in direction to the big and the small arrows, and subjects were cued to attend to either small or medium arrows