What is attentional control?

Attentional control (AC:)  "The ability to focus on task-relevant stimuli and ignore task-irrelevant stimuli.  The ability to regulate intentionality and direct cognitive processing.  Sometimes referred to as spotlight or focal attention, focus, control of attention, executive controlled attention or executive attention"(McGrew, LaForte, & Schrank, 2014; WJ IV technical manual).

AC is suggested to be a fundamental, possibly core, ability in understanding working memory capacity.