Pay Attention Meaning

(idiomatic, intransitive) To attend; to be attentive; to focus one's attention.

Example: 1913, Joseph C. Lincoln, chapter 4, Mr. Pratt's Patients:
  I was on my way to the door, but all at once, through the fog in my head, I began to sight one reef that I hadn't paid any attention to afore.
  Please pay attention to the danger signs.‎