I meant literally universal to ALL humans. Like, ones in comas, ones who are blind, deaf, autistic, mentally handicapped, super-savants, trained in rationality, illiterate... there's such a huge variation in hardware that I can't see there being a single guaranteed exploit.
Sure, it's possible that each individual has exploits, but that's very different from a universal exploit, or even simply all being exploitable over the same channel.
In this case, it was "arbitrary text string". If the AI can make sounds, that's a new channel. It's really not hard to design a text-only terminal that is literally incapable of any sound beyond the electronic hum of the display itself (and on an LCD, that seems pretty minimal)
it's possible that each individual has exploits, but that's very different from a universal exploit, or even simply all being exploitable over the same channel.
First, I'd call a collection of individual exploits guaranteed in aggregate to work on everyone from inside a single box a universal exploit, as long as each individual exploit does not trigger a shutdown. Nothing prevents the boxed AI from keeping trying, after all, until something works. As I pointed out in my other replies, it does not have to work over an authorized channel. Any munchkined wa...
Update 2013-09-05.
I have since played two more AI box experiments after this one, winning both.
Update 2013-12-30:
I have lost two more AI box experiments, and won two more. Current Record is 3 Wins, 3 Losses.