Deja Vu

[SpaceMarine93]

Does anyone here know what are the possible causes of Deja vus?

Because while I had experienced Deja Vu from time to time, just around the last month or so I suddenly got increasing numbers of it. Many things I never done and seen before look so familiar, and the effect even extends to when I surf the internet - I had impressions that I had read before images and articles online. I recently saw an picture online that was stated to be new, but for some reason I had distinct memory/impression that I had seen it somewhere before a long time ago.

And all this occured right after a period of exams and less than a day before I go on a plane trip home from university.

All this disturbs me. It could probably just be stress, or some other perfectly plausible scientific theory. I meanwhile can't shake off my fears that on some level something big is heading my way, and my subconscious mind for some reason could notice this and is trying to warn me. Irrational, I know.

Just in case... if I didn't write back in two days time, we would know either if it is irrational fear or something very unusual.

[Singular Intellect]

I recall reading that Deja Vu is a processessing error of the human brain, whereas there's a delay/doubling of sensory input and we perceive this as the experience of Deja Vu.

Don't recall the source nor can vouch for the accuracy of the idea.

[Korto]

I've had it a number of times where I'm doing something or watching something (or whatever) and I suddenly have this hazy memory of seeing this exact thing from years ago. If only I could go back five minutes, thereby wiping the current event from my memory, and then see if I could remember the event from years ago.

I've guessed the event gets accidentally mis-labelled in your brain with a "this happened a long time ago" tag.

[Alyrium Denryle]

I recall reading that Deja Vu is a processessing error of the human brain, whereas there's a delay/doubling of sensory input and we perceive this as the experience of Deja Vu.

Don't recall the source nor can vouch for the accuracy of the idea.

Have you ever taken intro psych in uni? If so, that is probably where you learned it. And yes, that is what happens.

[Rabid]

From my personal experience, if you are already prone to naturally experience Déjà Vu, I noted there was a positive correlation between your state of mental fatigue and the frequency/intensity of the "crises" : from a few times a month in "normal" situation, to several times a day in period of very high stress/mental workload.


Getting good nights of sleep and generally relieving yourself from the stress generally tend to improve the situation. I call it "defragmenting the drive", personally.


Note : If having these crises of Déjà Vu is so stressful to you that it increase the occurrence of the crises, well, you maybe should think about finding ways to relieve your stress AND get into your head that's it a perfectly natural thing, just an indicator that your head is fizzling a bit under the strain.
Personally, I find running or practicing a martial art (like Aikido), or even practicing archery (that's close to meditation in my mind...) to be a good way to relieve stress while focusing your mind on something. Else, going out with your friends and enjoying the company is a also a good bet.

[cadbrowser]

"defragmenting the drive" HAHA...I like that.

I have undergone many times where I've experienced this phenomenon. Lucky for me (when I was married) it helped me prevent a few arguments by "remembering" what had happened in my Deja Vu "memory" and changing it to be very pacifistic in nature thus avoiding any argument all together.

Wierd feeling. I remember reading a great deal of info on it from Wikipedia. I didn't take time to check every referenced work...but the "processing error in the human brain" was put forth on there. Was an interresting read.

[Humphnaegal]

When I was a kid, I used to have a variant of Deja Vu where when something happened, I had a flash of having already remembered it like normal DV, but with an extra event tacked on, so I was sure I could tell the future for the next 30 seconds.

I always failed.

[freker]

I had that feeling too, but to my mind it seemed like I really predicted the future for half a minute or so.
Very weird, but also very cool feeling.

[Singular Intellect]

I recall reading that Deja Vu is a processessing error of the human brain, whereas there's a delay/doubling of sensory input and we perceive this as the experience of Deja Vu.

Don't recall the source nor can vouch for the accuracy of the idea.

Have you ever taken intro psych in uni? If so, that is probably where you learned it. And yes, that is what happens.

Never took any such courses, no. I merely recall reading that as a very interesting piece of information and filed it away as something worth remembering. Came in handy when in conversation with one of my brothers who tried suggesting deja vu was probably something to do with the human brain existing at different levels of time or some stupid metaphysical shit. Apparently something as simple as 'the brain isn't perfect and induces perception errors on occasion' never crossed his mind. The human tendency to elevate the human brain to such ridiculous levels of complexity and supernatural concepts is annoying as fuck.

[Dave]

When I was a kid, I used to have a variant of Deja Vu where when something happened, I had a flash of having already remembered it like normal DV, but with an extra event tacked on, so I was sure I could tell the future for the next 30 seconds.

I always failed.

I had this happen once or at most twice, but was never able to "replay the memory faster than real-time", so to speak.

Some vague memory from Intro Psych tells me that Deja Vu was simply the brain mis-categorizing reality as a memory. Which seems plausible to me especially considering (as I understand it) that memory is not perfect and relies extensively on re-constructing the event rather than having some photographic memory. So, considering what a wiring mess the brain is, I see no reason why the brain couldn't accidentally reconstruct <the inputs we perceive as> reality as a memory.

[Ziggy Stardust]

It's also related to the same neural mechanism that makes your dreams seem linear and cohesive. In reality, your dreams are completely random, but your brain isn't wired to accept random input, or to ignore input, so it retroactively reconstructs this random noise into as linear a "story" as possible. It interprets the firings according to memories/sensations that invoked vaguely analogous responses in your brain, and basically "builds" the dream from these associative links.

[Singular Intellect]

It's also related to the same neural mechanism that makes your dreams seem linear and cohesive. In reality, your dreams are completely random, but your brain isn't wired to accept random input, or to ignore input, so it retroactively reconstructs this random noise into as linear a "story" as possible. It interprets the firings according to memories/sensations that invoked vaguely analogous responses in your brain, and basically "builds" the dream from these associative links.

That's a fascinating piece of information on the human brain. Potentially another handy fact to file away for those inevitable times people try and dress up dreams as some sort of supernatural pseudoscientific bullshit used to feed the human notion of how special and magical we are.

[cadbrowser]

Hey Ziggy, where did you read that from? I'd be highly interrested in picking up that book or article. Sounds very interresting.

[Ziggy Stardust]

Hey Ziggy, where did you read that from? I'd be highly interrested in picking up that book or article. Sounds very interresting.

Off of the top of my head I can't give you a single good book/article that covers the issue in depth. I work in cognitive psychology, and my knowledge of this is mostly gleaned from presentations and talks with people who study dreams (I work with language, so I must admit that this isn't precisely my field), and reading of assorted literature. There is an older book called "The Dreaming Brain" by J Allen Hobson which is very good, but it was written in the late 1980s, and obviously isn't completely up to date. It is worth reading, though, for Hobson's theories of dream synthesis, many of which have been proven at least partially correct. Here is an introduction to a more recent book, which glances over some of the data; it is pretty interesting, and the citations at the end can lead you to more on the subject.

Also, to be fair, the process is a LITTLE more complicated than I outlined in the previous post.

There are actually two separate (but, I must add, not mutually exclusive) neurological theories of dream generation (actually, to be perfectly accurate, there are plenty of others, as well, but these ones seem to me to have the greatest empirical backing ... the fields of psychology and cognitive science are often cluttered by rather non-scientific methodology). Anyway, it all begins with the activation-synthesis hypothesis, which is an observable phenomenon during sleep; at its simplest level this simply states that there are measurable differences in brain activity during REM sleep than when you are awake. One theory states that there is a randomness to these activation patterns, and thus to the synthesized dream imagery generated by your brain to fit these patterns with internally generated ones - this is what I said in the previous post, how your brain tries to make sense of the activation by matching it with similar activations from when you are awake. The other theory is that the brain can be modeled as a network of associative neural nets, and that when disconnected from usual input/output connections (which happens when you fall asleep ... most sensory and motor networks are deactivated), the nets become "overloaded" with random input, and dreams are the side-effect of this process - part of which involves pseudorandom activation of semantic and episodic memory.

Here is a good paper that reviews these, and other, theories.

As for the actual mechanism of this action, the most relevant theory is that it is related to PGO (ponto-geniculo-occipital) waves, which are brain stem-generated field potentials that are often generated during the early stages of REM sleep. These waves activate areas of the forebrain, especially those related to visual processing. However, during sleep access to most sensory/motor networks is blocked (parts of the brain, especially the dorsolateral frontal convexity, are literally turned "off"), and activation ends up spreading "backwards" to perceptual areas of the brain, such as the parieto-occipital-temporal junction - a part of the brain responsible for higher-end perceptual tasks, such as abstract thoughts and memories, and mental imagery. The brain compares patterns of activation in these areas of the brain with information stored in active memory. This is the primary neurophysiological factor in dream synthesis (though there are other factors - importantly, the inactivation of the limbic brain pathways, which is responsible for your brain "thinking" the dream is really happening, essentially). Here is a paper that touches on some of this research.

[cadbrowser]

Wow, cognitive phsycology? Sounds extremely facinating in and of itself!

Thank you so much for the overview, the book recommendation, and the links. I will see about reading through them as well as seeing if I can find that book at the library the next time I go.