Through our senses, that provide streams of sense data. Eyes detect light, organized into images that fall on the retina. Ears detect sound, organized into a frequency spectrum that resonates in the cochlea. The nose detects trace concentrations of aromatic chemical compounds in the air.
Taste detects chemical compounds in the mouth.
Through the use of cybernetic feedback loops. Each sense processes the incoming signals from the very beginning of their passage through the perception process. A generic control circuit has two nodes, one at the input of processing, the other at the output. Control loops are linked together in a hierarchical ladder of loops. Lower order loops deal with individual properties of their sense.