http://stuffucanuse.com/topics/head_chopped_off.htm A particularly detailed report comes from Dr Beaurieux who, under perfect circumstances, experimented with the head of the murderer Languille, guillotined at 5.30 am on 28 June, 1905.
(From A History of the Guillotine by Alister Kershaw. His source is Archives d'Anthropologie Criminelle, 1905):
Here, then, is what I was able to note immediately after the decapitation.
The eyelids and lips of the guillotined man worked in irregularly rhythmic contractions for about five or six seconds. I waited for several seconds. The spasmodic movements ceased.
The face relaxed, the lids half closed on the eyeballs, leaving only the white of the conjunctiva visible, exactly as in the dying whom we have occasion to see every day in the exercise of our profession, or as in those just dead.
It was then that I called in a strong, sharp voice: 'Languille!'
I saw the eyelids slowly lift up, without any spasmodic contractions.
Next Languille's eyes very definitely fixed themselves on mine and the pupils focused themselves.
After several seconds, the eyelids closed again, slowly and evenly, and the head took on the same appearance as it had had before I called out.
It was at that point that I called out again and, once more, without any spasm, slowly, the eyelids lifted and undeniably living eyes fixed themselves on mine with perhaps even more penetration than the first time.
Then there was a further closing of the eyelids, but now less complete.
I attempted the effect of a third call; there was no further movement and the eyes took on the glazed look which they have in the dead.
"I have just recounted to you with rigorous exactness what I was able to observe.
The whole thing had lasted twenty-five to thirty seconds."
its very debatable
but i believe that there is still blood in ur brain when ur decapitated.
and ur brain can survive a few seconds with out o2
people use to say that when people were guillotined
that they would blind in a way that would tell them that they did it
for ex. they ask them did they do it 1 blink no 2 for yes.
i honestly believe that u are still conscious for a few seconds