As the answerer, if you have a wide vocabulary or if you're a technical person then it's not too difficult to routinely choose words the other person simply does not know so that no amount of yes/no questions will get them there.
Obscure medical terms (phlebotomy), names of uncommonly-known stars (Fomalhaut), obscure data structures (cache-oblivious lookahead arrays), mathematical constants (Feigenbaum's constants)... The list goes on and on!
The point I'm trying to make is that most people who play Twenty Questions aren't trying to maximize the number of bits per second in their answer. They're actually trying to play semi-cooperatively. The fun part of Twenty Questions is when the other person guesses your word with as few questions remaining as possible. Having them get all the way to 20 and then you tell them "no you were way off to guess toothache, it was actually temporomandibular joint dysfunction" makes you look rather unsporting!
Thus, since I think we can expect people who play Twenty Questions to actually try to choose a word they know the other person can guess within the space allowed, we can reasonably conclude that using the game as a way to establish some sort of rough constraint on the speed of thinking (in bits per second) is way off. In fact, I know from my own experience playing the game that I will think of and discard many words in a short time as I try to find one that will be in the sweet spot of challenge for the other person to guess.
Obscure medical terms (phlebotomy), names of uncommonly-known stars (Fomalhaut), obscure data structures (cache-oblivious lookahead arrays), mathematical constants (Feigenbaum's constants)... The list goes on and on!
The point I'm trying to make is that most people who play Twenty Questions aren't trying to maximize the number of bits per second in their answer. They're actually trying to play semi-cooperatively. The fun part of Twenty Questions is when the other person guesses your word with as few questions remaining as possible. Having them get all the way to 20 and then you tell them "no you were way off to guess toothache, it was actually temporomandibular joint dysfunction" makes you look rather unsporting!
Thus, since I think we can expect people who play Twenty Questions to actually try to choose a word they know the other person can guess within the space allowed, we can reasonably conclude that using the game as a way to establish some sort of rough constraint on the speed of thinking (in bits per second) is way off. In fact, I know from my own experience playing the game that I will think of and discard many words in a short time as I try to find one that will be in the sweet spot of challenge for the other person to guess.