Pain withdrawal reflex

Overview
The pain withdrawal reflex is an involuntary action in which the body reacts to pain by trying to move itself away from the source of the pain, to reduce or even eliminate that pain.

Although this is a reflex, there are two interesting aspects:

(1) the body can be trained to over-ride that reflex; and

(2) an unconscious body (or even drunk or drugged bodies) will not exhibit the reflex.