# Generating randomness using the human brain [closed]

I have seen this question on programmers.StackExchange, and I'd like to have math's advice.

What is a suitable way to generate (pseudo-?) random numbers using (mainly) the brain?

Ultimately, I'm trying to find a way to create a mental process, based on a probability p, that could return success or failure on each trial with probability p. I would derive that process from the random number generation question, which I thought was more generally usable.

The process would be chosen based on/meet the following criteria:

• Can be done by the brain, in sat position, and one hand is available (some usage of the body is acceptable)
• Is relatively stealth (result can't/is hard to be seen by others)
• Can be generated repeatedly in a relatively short period of time (1/30 s. is acceptable)

Some methods I have found so far:

• Wearing a watch, looking at the seconds hand. Con: Can't be repeated before some time. (2-5 minutes?)
• Wearing a Pebble watch with an app for generating random numbers on it. Con: not really stealth, needs tools other than brain
• Rely on external events, e.g. name a word on sight. Con: Hard to repeat, environment not so random
• The accepted answer on the other question, involving a small LCG. Con: small number of streams; as random as the seed (?)
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This strikes me as more of a question about the brain than a question about mathematics, and so is not really appropriate for math.SE. My experience is that the brain is terrible at being pseudorandom and this is corroborated by the fact that competitive rock-paper-scissors exists. –  Qiaochu Yuan Apr 18 '12 at 4:50
@QiaochuYuan Can you suggest a better place for this question? –  jonallard Apr 18 '12 at 4:53
Maybe cogsci.stackexchange.com? I'm not sure. –  Qiaochu Yuan Apr 18 '12 at 4:54
Anyway, if you have a digital watch with a timer, it might display tenths and hundredths of seconds, in which case looking at those digits strikes me as potentially a good idea. –  Qiaochu Yuan Apr 18 '12 at 5:02
A more acceptable version of this question: "What mental math techniques could efficiently generate random numbers?" –  anon Apr 18 '12 at 5:24