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Comment by trishume | Hacker News Reader

Hypothesis: Deja Vu happens when the long term memory isn't suppressed properly during the first few days.

I often find when I experience Deja Vu I think I remember doing a thing I did the day before a long time before that. It feels like I have two memories, one of a recent event and one a vague recollection of something a long time ago. This sounds like exactly what one would expect if two memories are recorded, one suppressed for a few days and one forgotten in a few days, but the suppression fails.

Does anyone else have Deja Vu like this?

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Since our brains store a simplistic version of what our sensors actually read, my WAG Hypothesis is that Deja Vu happens when the digested patterns ready for storage, collide with previous experiences in memory. Kind of a hashing collision.

In my experience Deja Vu doesn't happen for something I remember doing yesterday, but something I'm currently doing right now, or some combination of events that just occurred. But either way, that's a good hypothesis.

This matches my experience. Deja vu is not something I remember from a past event, but from something happening right at the moment. If I understand the article correctly, and a candidate theory for deja vu encountered on Wikipedia, this might make sense.

I think the theory is that occasionally there are slight issues with the timing/synchronization of the memory being stored in certain parts of the brain. Since the research shows that memories are written twice, if such a desync occurred, maybe deja vu is some perception of disagreement between short and long term memories?

For some reason, I find the experience of deja vu somehow quite ... pleasing. I am not sure if this is true for everyone.

As a kid I found deja vu pleasing as well and "practiced" it for a long time, "giving myself" deja vu.

I would practice by doing the same thing I did the day before or a week before, then try to focus on the feeling and enhance it as soon as it started to show up, then kind of "let myself live in deja vu" for longer and longer periods.

Now I can give myself that feeling anytime. I first relax and look around, take in as much as I can. Then go back to doing something else, then relax again and pretend I have already been where I am.

When I have Deja Vu it's very clear to me that what I'm doing _right now_, in this second, is something that's happened before. I sometimes have experiences where the Deja Vu occurring in the present is possibly the _third_ time that it's happened as well. It just feels so familiar in multiple ways that I am reminded of something happening a while back.

Such an odd sensation when your brain is telling you you're experiencing a repeated situation, but your mind is telling you it's impossible.

Short term memory isn't a matter of days, it's a matter of seconds and minutes. But otherwise, that makes sense. In fact, I think this is already a hypothesis which has come out of fMRI?

There's a second part to a Deja Vu phenomenom that often gets overlooked... the feeling that you've had this experience before is coupled with the ability to predict what will happen next based on the 'memory'.

Next time you get deja vu, try to "remember" what happens next. It's scarily accurate after you willingly try it once or twice.

My overall hypothesis is somewhat inline with yours (although I don't have nearly the expertise to properly examine these things) - that somehow the brain 'skips' filing the memory properly, and the experience being recalled milliseconds later as "now" is being mis-remembered as "past".

Very cool machine our brain.

Deja Vu happens when they change something in the Matrix.

This is the correct explanation

https://www.youtube.com/watch?v=z_KmNZNT5xw

I've had a few Deja Vu experiences that felt so incredibly real, like I had experienced precisely this before, but my memory tells me for sure I've never gone through anything similar.

Is this because the clearer "short term" version is completely lost?

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