# Do we know how the human brain generates random numbers? **URL:** \ **Category:** Factual Questions\ **Created:** [December 11, 2010, 5:12am UTC](https://boards.straightdope.com/t/do-we-know-how-the-human-brain-generates-random-numbers/563761 "2010-12-11T05:12:25Z")\ **Posts on this page:** 17\ **Page:** 2
**Author:** ![BigT](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bigt/32/12044_2.png) [@BigT](https://boards.straightdope.com/u/BigT)\ **Post date:** [December 12, 2010, 2:25am UTC](https://boards.straightdope.com/t/do-we-know-how-the-human-brain-generates-random-numbers/563761/21 "2010-12-12T02:25:55Z")
I thought my point would be pretty clear: if humans produce certain patterns when producing random numbers, that means that is how they are defining the word random. The word pseudorandom is specifically defined in computer circles as having to do with preconceived tables. I see no indication that most humans have such a table, so they don’t fit that definition of pseudorandom. It you want to just use it to mean “false random”, and define random in the mathematical sense, that’s fine. But don’t assume someone else is doing the same. I’d say that pseudorandom in the computer sense is more random in the mathematical sense than random in the colloquial sense. ---
**Author:** ![Mijin](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mijin/32/9369_2.png) [@Mijin](https://boards.straightdope.com/u/Mijin)\ **Post date:** [December 12, 2010, 1:14pm UTC](https://boards.straightdope.com/t/do-we-know-how-the-human-brain-generates-random-numbers/563761/22 "2010-12-12T13:14:16Z")
> [@BigT](#): > > I thought my point would be pretty clear: if humans produce certain patterns when producing random numbers, that means that is how they are defining the word random. Like many English words, there are different meanings for the word “random”. And, indeed, in some contexts we may mean “human-like random”. For instance, if I ask someone to make a choice “at random”, I don’t expect them to become a RNG, I just mean “make a choice with little conscious thought”. And sometimes we mean in the statistical sense where every number has an equal chance of being generated and there is (eventually) no pattern. Certainly we mean this definition when discussing gambling / lotteries / prize draws, for instance. I think in the context of “generating random numbers”, the statistical sense is far more likely. The OP even discusses whether the distribution of human-generated numbers is truly random…so it’s pretty clear what meaning (s)he has in mind. ---
**Author:** ![HMS\_Irruncible](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hms_irruncible/32/7394_2.png) [@HMS\_Irruncible](https://boards.straightdope.com/u/HMS_Irruncible)\ **Post date:** [December 12, 2010, 2:10pm UTC](https://boards.straightdope.com/t/do-we-know-how-the-human-brain-generates-random-numbers/563761/23 "2010-12-12T14:10:45Z")
> [@DarrenS](#): > > When you ask a human to generate random numbers, they’ll come up with a series of values. > > Do we have any idea what mechanism in the brain is used for this? It’s the mechanism responsible for generating non-random patterns of numbers. ---
**Author:** ![ZenBeam](https://avatars.discourse-cdn.com/v4/letter/z/3ab097/32.png) [@ZenBeam](https://boards.straightdope.com/u/ZenBeam)\ **Post date:** [December 12, 2010, 2:31pm UTC](https://boards.straightdope.com/t/do-we-know-how-the-human-brain-generates-random-numbers/563761/24 "2010-12-12T14:31:58Z")
> [@BigT](#): > > I’d say that pseudorandom in the computer sense is more random in the mathematical sense than random in the colloquial sense. That’s going to depend on what you mean by “more random”. Random in the colloquial sense at least has some element of randomness in the mathematical sense. Pseudorandom, however, is deterministic. ---
**Author:** ![Asympotically\_fat](https://avatars.discourse-cdn.com/v4/letter/a/e47c2d/32.png) [@Asympotically\_fat](https://boards.straightdope.com/u/Asympotically_fat)\ **Post date:** [December 12, 2010, 3:04pm UTC](https://boards.straightdope.com/t/do-we-know-how-the-human-brain-generates-random-numbers/563761/25 "2010-12-12T15:04:09Z")
> [@BigT](#): > > I thought my point would be pretty clear: if humans produce certain patterns when producing random numbers, that means that is how they are defining the word random. > > The word pseudorandom is specifically defined in computer circles as having to do with preconceived tables. I see no indication that most humans have such a table, so they don’t fit that definition of pseudorandom. It you want to just use it to mean “false random”, and define random in the mathematical sense, that’s fine. But don’t assume someone else is doing the same. > > I’d say that pseudorandom in the computer sense is more random in the mathematical sense than random in the colloquial sense. Pseudorandom means using a deterministic algortihm (i.e. deterministic procedure) to produce a sequences of numbers with a probabilty distibution (usually uniform). For me though pseudorandom may very well fall under the colloquial defintion of random. Humans when asked to produce sequences of random numbers try to produce sequences which follow a uniform distribution, but aqren’t as good at it as computers. Now the question of whether they are basically (poor) pseudorandom number generators (i.e. follow a deterministic procedure) or whether there is some elemnt of the procedure that can be defined in some way as non-deterministic is the whole crux of the OP. Myself examing how _I_ would choose a random number if asked (I am after all described as human in some circles) can’t see any elements in the procedure I use that are more non-deterministic (if 'more non-deterministic’isn’t an oxymoron) than the procedure that a pseudorandom number generator would use. ---
**Author:** ![Asympotically\_fat](https://avatars.discourse-cdn.com/v4/letter/a/e47c2d/32.png) [@Asympotically\_fat](https://boards.straightdope.com/u/Asympotically_fat)\ **Post date:** [December 12, 2010, 3:13pm UTC](https://boards.straightdope.com/t/do-we-know-how-the-human-brain-generates-random-numbers/563761/26 "2010-12-12T15:13:28Z")
Or maybe it wasn’t quite the crux of the OP, but the question about the distibution of numbers produced by humans has already been answered. ---
**Author:** ![heavyarms553](https://avatars.discourse-cdn.com/v4/letter/h/779978/32.png) [@heavyarms553](https://boards.straightdope.com/u/heavyarms553)\ **Post date:** [December 12, 2010, 3:30pm UTC](https://boards.straightdope.com/t/do-we-know-how-the-human-brain-generates-random-numbers/563761/27 "2010-12-12T15:30:28Z")
Think of it this way, if someone asked to to select three random numbers between one and ten, would you ever reply with three identical numbers? In other words, would you ever reply 5, 5, and 5? Math tells us the likelihood of that occurring should be 1 in 1000 if the human random number generation process was truly random. That being said, no one ever gives that reply. ---
**Author:** ![Alessan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/alessan/32/465_2.png) [@Alessan](https://boards.straightdope.com/u/Alessan)\ **Post date:** [December 12, 2010, 4:17pm UTC](https://boards.straightdope.com/t/do-we-know-how-the-human-brain-generates-random-numbers/563761/28 "2010-12-12T16:17:20Z")
> [@heavyarms553](#): > > Think of it this way, if someone asked to to select three random numbers between one and ten, would you ever reply with three identical numbers? In other words, would you ever reply 5, 5, and 5? Math tells us the likelihood of that occurring should be 1 in 1000 if the human random number generation process was truly random. That being said, no one ever gives that reply. 1 in 100. (5, 5, and 5 is 1 in 1000, of course, but it doesn’t have to be 5). ---
**Author:** ![ultrafilter](https://avatars.discourse-cdn.com/v4/letter/u/3d9bf3/32.png) [@ultrafilter](https://boards.straightdope.com/u/ultrafilter)\ **Post date:** [December 12, 2010, 7:48pm UTC](https://boards.straightdope.com/t/do-we-know-how-the-human-brain-generates-random-numbers/563761/29 "2010-12-12T19:48:49Z")
> [@These are my own pants](#): > > Mathematics doesn’t have an absolute definition of random. The word usually means something along the lines of ‘stochastic’ i.e. modelled by probabilty theory. What’s more the distrbution is usually assumed (unless otherwise stated) to be uniform. There are a couple mathematical definitions of randomness, and neither of them has anything to do with stochastic models. A sequence of numbers is said to be random if it is either incompressible or hard to predict (both of which can be given much more precise meanings). Of course, the two notions are related in some non-trivial way, but there’s usually one that’s more appropriate for any given situation. > [@](#): > > The funny thing is that non-random computers are actually pretty good at guessing what people will say when asked to give a random string of numbers. Do you have a reference for this? I’ve heard the same thing, but I haven’t been able to find any specifics. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [December 12, 2010, 8:18pm UTC](https://boards.straightdope.com/t/do-we-know-how-the-human-brain-generates-random-numbers/563761/30 "2010-12-12T20:18:52Z")
Certainly computers can beat humans pretty consistently at paper-rock-scissors, even when the human is trying to play randomly. That effectively boils down to predicting random strings of numbers, though drawn from a very small alphabet. Quoth **TriPolar** : > [@](#): > > First, what’s not random about the number 56? Or 23? > > Second, what’s random about a single number? [Obligatory XKCD](http://xkcd.com/221/) And on a less serious note, I have found that there are ways to get humans to produce truly random numbers, like putting a physics test in front of them. ---
**Author:** ![DarrenS](https://avatars.discourse-cdn.com/v4/letter/d/977dab/32.png) [@DarrenS](https://boards.straightdope.com/u/DarrenS)\ **Post date:** [December 12, 2010, 10:23pm UTC](https://boards.straightdope.com/t/do-we-know-how-the-human-brain-generates-random-numbers/563761/31 "2010-12-12T22:23:42Z")
> [@Chronos](#): > > And on a less serious note, I have found that there are ways to get humans to produce truly random numbers, like putting a physics test in front of them. Funny you should mention – when I was at college, I remember seeing other students trying to put random values on multiple-choice homework assignments. But they’d say things like, “Hmm…three Bs in a row…can’t have that – I’d better mix it up a bit.” Yes, the kind of randomness I’m curious about is that described by **ultrafilter**. Not computer-like pseudorandomness, and not “colloquial” randomness either. ---
**Author:** ![Hari\_Seldon](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hari_seldon/32/5173_2.png) [@Hari\_Seldon](https://boards.straightdope.com/u/Hari_Seldon)\ **Post date:** [December 12, 2010, 10:50pm UTC](https://boards.straightdope.com/t/do-we-know-how-the-human-brain-generates-random-numbers/563761/32 "2010-12-12T22:50:36Z")
When picking a random number between 1 and 100, I avoid multiples of 2, 3, 5, or 7. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [December 12, 2010, 11:00pm UTC](https://boards.straightdope.com/t/do-we-know-how-the-human-brain-generates-random-numbers/563761/33 "2010-12-12T23:00:15Z")
> [@](#): > > Funny you should mention – when I was at college, I remember seeing other students trying to put random values on multiple-choice homework assignments. But they’d say things like, “Hmm…three Bs in a row…can’t have that – I’d better mix it up a bit.” No, I’m not referring to the multiple choice. I mean the kind of problem-solving that leads to answering questions like “what is the speed of the proton?” with answers like “3.2_10^-43 m/s", or "6_10^30”. ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [December 13, 2010, 3:50am UTC](https://boards.straightdope.com/t/do-we-know-how-the-human-brain-generates-random-numbers/563761/34 "2010-12-13T03:50:29Z")
> [@Chronos](#): > > No, I’m not referring to the multiple choice. I mean the kind of problem-solving that leads to answering questions like “what is the speed of the proton?” with answers like “3.2_10^-43 m/s", or "6_10^30”. I was pretty sure physics would give us another definition for random. ---
**Author:** ![HMS\_Irruncible](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hms_irruncible/32/7394_2.png) [@HMS\_Irruncible](https://boards.straightdope.com/u/HMS_Irruncible)\ **Post date:** [December 13, 2010, 12:41pm UTC](https://boards.straightdope.com/t/do-we-know-how-the-human-brain-generates-random-numbers/563761/35 "2010-12-13T12:41:42Z")
> [@Chronos](#): > > No, I’m not referring to the multiple choice. I mean the kind of problem-solving that leads to answering questions like “what is the speed of the proton?” with answers like “3.2_10^-43 m/s", or "6_10^30”. African or European? ---
**Author:** ![psychonaut](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/psychonaut/32/4655_2.png) [@psychonaut](https://boards.straightdope.com/u/psychonaut)\ **Post date:** [December 13, 2010, 1:09pm UTC](https://boards.straightdope.com/t/do-we-know-how-the-human-brain-generates-random-numbers/563761/36 "2010-12-13T13:09:19Z")
> [@engineer\_comp\_geek](#): > > Computers most often use the timer tick as a seed value into a pseudorandom sequence. On rare occasions you’ll see mouse movements and the like used, but most often they just get the current system timer value. There are some computers that have true random number generators in them, which are usually constructed out of white noise circuits, but you won’t find this sort of thing in a typical home computer. Your information is about 20 to 30 years out of date. The system pseudorandom number generators (/dev/random and /dev/urandom) on modern \*nix operating systems, including Linux and Mac OS X, are seeded from several environmental sources, not just the system timer. The resulting numbers are sufficiently random to be used in cryptographically secure applications. I would be (mildly) surprised if recent versions of Microsoft Windows did not have similarly powerful PRNGs. ---
**Author:** ![ultrafilter](https://avatars.discourse-cdn.com/v4/letter/u/3d9bf3/32.png) [@ultrafilter](https://boards.straightdope.com/u/ultrafilter)\ **Post date:** [December 13, 2010, 4:26pm UTC](https://boards.straightdope.com/t/do-we-know-how-the-human-brain-generates-random-numbers/563761/37 "2010-12-13T16:26:02Z")
Here’s a paper that might be interesting: [Effective indices to characterize short sequences of human random generations](http://www.springerlink.com/content/h2x6240v54484920/) > [@](#): > > Brain impediments such as dementia are a serious problem today. It would be very useful if software for private diagnosis were available. In this paper, we show the effectiveness of the human random generation test (HRG) for such software, and propose a set of four indices to be used for classifying the HRG data. Human-generated random numbers have strong characteristics compared to computer-generated random numbers, and these are known to be correlated to the individual characters of the subjects. However, analysis using the correlation dimension or HMM requires a long data sequence, and thus is not suitable for diagnoses. > > We therefore focus on short sequences of HRG and search for effective indices to detect signs of brain disability hidden in the HRG data. We studied data from subjects of different age groups, and successfully differentiated the data from the different groups. The references will probably be interesting too. [Previous page](https://boards.straightdope.com/t/do-we-know-how-the-human-brain-generates-random-numbers/563761.md?page=1)