The first rule for activity selection is that cues have got to capture the person's attention. Ignored cues are useless. Within ACL 4, cues are grouped or classified to assist the person with making their selections.
The person's information processing system synthesises the information into a new experience that is: evaluated, compared with other experiences, and a choice is made about whether to sustain their attention, or not.
Sustained attention is a combination of personal choice and available mental energy.