Question

Is the phenomenon where your ability to detect a constant sensation decreases the longer you feel it?

Answer 1

The phenomenon is tolerance.
Tolerance can be found in many aspects of physiology,
For example, when you feel a pain somewhere due to touching something sharp, the feel will be less intense when you feel it the next times.
When you eat a lot of sweets, you tung will temporarily lose its ability to feel sugars
Another example in pharmacology, when you drug in a chronic way, its effect will decrease.