There is a test for psychological vs. physical coma that may not awaken the victim, and which
does not cause vomiting, unlike
the ice water method. It may be useful
in certain circumstances.
Assuming the victim is lying on their back, raise their hand directly above their face and drop it. A physically comatose victim will permit the hand to fall directly on the face, and you need to get a doctor involved to prevent any further resemblance to a rag doll. A psychologically comatose victim will sense the threat and just manage to pull the hand to one side.
Side effects may include a broken nose—the victim's, if the coma was physical, or yours, if the victim finds your intrusion upsetting enough. Use with caution.
This writeup was brought to you today by my Physiology prof Bruce Woolley, my EMT friends Erika and Sterling, and the indefinite 'they'.