The ability to pay attention selectively, ignoring distractions, develops throughout childhood at least until adolescence. So does the ability to shift attention quickly and efficiently.
-Sharon Begley quoting Helen Nelville in Train Your Mind, Change Your Brain. (p160).
Begley goes on to say that as we age our ability to suppress unattended inputs increases. Brain signals associated with what we do not pay attention to decreases with age. (p160)
This growing ability (or tendency) to suppress information could help us keep focus on a particular object or particular kinds of objects and thus maintain calm and stillness or other wholesome qualities of mind - or it could keep us trapped in delusion. It might be easier to miss valuable information.
There are good reasons for being tightly or broadly focused depending on circumstances. It seems wise to maintain flexibility of attention so we can interact skillfully. Awareness of the quality of attention and the degree of attention needed in any given situation is an important skill.
