They are very powerful computing devices, indeed, but they do have their limits. Let me explain…
They do not have the power to compute time and advanced mathematical equations. This is why looking at a digital watch, looking away, and looking back is such a great RC. It’s because the human brain, in it’s natural state, is not fast enough to keep track of time! I have to go eat now, but when I get the time I would be happy to further expound.
The human brain is not fast enough? I somehow can’t buy into that. In fact, just recently I watched a documentary that explained deja vu as a memory of what the brain didn’t have time to adjust to and you see it as a delay. Which I still don’t believe that. Not enough information to convince me.
And how are digital watches a good RC? Is it because the numbers change?
Human brain has the power to compute complex textures, as you can see in very vivid LD’s, he has the power to compute complex mathematical formulas (it has been shown recently that you can approximate every formula with a quite simple neural network, and the human one is nowhere near to be simple).
On the other hand, he has the power to do that if it is in his normal state. What is not the case in every dreams. Xetrov said in another post that there is a sleep stage in which visual parts of the brain are switched off. And there is a special dream state, quite OBE’ish or SP’ish, in which the environment is generally dark or greyish and very few detailled. Generally, “shadow persons” appear in such an environment and their “image treatment” is as poor as the remaining.
I have to disagree. The mechanism behind this RC is that when you are dreaming, nearly 100% of the logical awareness (we do all kinds of “stupid” things because of this in our dreams) in the brain is switched off. Combine this with an approximate internal representation of external objects, and you can acount for most if not all dream inconsistencies.
Explained more simply: You dream. You RC; the clock sais 2:34. The RC is somewhat mechanical, you are not yet highly lucid. So you do not force the brain to show 2:34 again next time you look (something you can do when higly lucid). Thus why should the brain follow IRL clock/time logic? The brain sais “screw it, next time i’ll show [insert random time]”
This explanation seems as least as plausible and probably even more likely to be true then the “brain fails to compute” idea.
I too have had an experiance with a shadow person. As a matter of fact it was a terrible nightmare I had when I was very young. One of the worst.
As a matter of fact my first ever lucid dream occured in this nightmare. Just before he attacked I found that I was dreaming.
When he attacked I merely shoved him on to the ground. Once he hit the ground he burst into a thousand colors that floated up into the air. I never had that nightmare again.
According to Stephen LaBerge, Ph.D, on his CD that accompanied the book Lucid Dreaming he states the brain is flawed and that it is not able to keep time in an orderly sequence due to the fact it is only so powerful.
Sorry if you don’t want to believe that, but I am taking my words straight from a trusted man with more than 10 years of lucid dreaming experience.
I didn’t intervene about the time stuff, because it sounds far more complicated than it looks like at first sight. First of all, what do you think about that?
Your clock?
It happens to me in waking state very often. Some people are able to know the time very precisely without a clock (for instance, former french president François Mitterand was well-known for knowing the time within about five minutes). A night when I was quite drunk 
, a friend asked me thrice what time it was and I said him thrice the precise time (with exact minute).
And it’s a very common experience that you wake up just few seconds before your clocks rings. Some people don’t need a clock, they can wake up at the time they want.
Our inner clocks and rhythms (circadian cycle for instance) are quite precise. And about Laberge, he did an experiment about time in LD’s:
so that I’m very surprised when you quote him saying brain was not able to compute time in LD’s.
That the reasons why I suspect the clock RC results not to be related with our brain “poor” computational abilities (just notice that no computer is able up to now to compute, treat and transform vision the way we do in about 40 milliseconds). It seems to me obvious that we could perfectly look at a dream clock, see 4:13, look anywhere then look back at our clock and see 4:13 again without our requiring a great computational effort!
Moreover, as this clock time is dreamt, it’s not the true time, so that it has nothing to do with real time computation indeed.
In conclusion, I agree with Xetrov’s algorithm:
For i = 1 to n
Look at the clock
Insert random time
End for 
I’ve heared people with 60 years experience in certain subjects rable complete nonsense before. This is not an argument. Stating the exact experiments Laberge did and how he reached that conclusion would be (or linking an article or so).
Question:
Last night I appeared in a mirror as a shadow. Shouldn’t my brain know what I look like without having to think too hard?
i became lucid in a small dark room, the room had no door or windows, but it had a mirror in the room, i don’t know about you guys but i love walking through them:)
i walked through the mirror, normally when i walk though a mirror, i appear in a other room, but this time, i found my self in what can be best described as being, in a pipe-line-wave/ or a worm hole looking thing, i stayed in there for as long as i could, i would’ve stayed longer, or even better still, get to the other side, but for some reason, i felt like i couldn’t breath, like i was drowning, so i walked back out of the mirror.
as soon as i got back out of the mirror, my head was buzz-in, my senses were going absolutely crazy, my psychic sesnes anyways, hard to describe sorry, but i knew something was near, i started to turn around and around, to better cover the room to see if someone else was there.
suddenly and unexpectedly I’m bear hugged from behind, and i was shocked more then scared, thinking wtf have i gotten my self into, this doesnt feel right!.
he whispered all sorts of nasty stuff into my ear, i truely forget what he said now, mainly because i wasnt really listening, but anyhows, as he was ranting into my ear, i was silently invesigating him, i was feeling his arms that held me, felt human like kinda i guess, even had under arm hair! dont know if it means anything though
but i had to get my self out of this somehow.
i brought all my knowledge into mind, ok this is funny, but i started to hum the smurth song:).
this actually produced laughter from this being, and he losened his hold, and i used that time to get away… my first experience with them, not my last,
i know there weakness now…i believe they are real…
If a shadow person ever gives you trouble in a lucid dream or while astral projecting, summon a LIGHT SWORD. The blade is to be crafted literally of pure, white light. It should emit a golden/white aura as well. Really, you summon one of these bad boys and stab the S.O.B. in the chest, you won’t EVER see that shadow again. I guarantee, he will tell his friends as well to keep far away from you.
No way I’ll be takin any crap from anyone in MY dreams! 
Best game ever lol!
I think you should try to contact him again and ask him who he is and what he wants. Especially if you didn’t find it menacing.
Before? What if it’s like a reoccuring dream, it is a problem or conflict that your subconsious wants you to solve? You should face the shadow person again and ask him what he wants.
Then it probably isn’t bad. It’s probably just trying to tell you something.