Even The Blind Get Deja Vu

zentropa writes "Cosmos magazine is reporting that even the blind experience deja vu — backing the idea that it is caused by misfires in the brain's temporal lobe. They quote a British study where a blind man feels like he has 'already seen' some unfamiliar situations. 'Hearing and touch and smell often seem to intermingle in the déjà vu experiences,' said the study subject, whose name has not been made public. 'It is almost like photographic memory, without sight obviously... as if I was encountering a mini-recording in my head, but trying to think "Where have I come across that before?"'"

Comments

No big surprise.

[wickedsteve]

I am sure I am not the only one who is not the slightest bit surprised. In fact I would be surprised if anyone told me that their deja vu exprience was primarily visual.
Every time I have had it it was a feeling of actually re-living the moment in every way and detail even down to the actions and thoughts I had seeming strangely familiar.
For me deja vu has been a completely immersive experience where no single one of my senses was predominant.

Thought this would be a deep philosophical article

[UpnAtom]

... given the title. After all, who could actually think the blind couldn't get deja vu?

Re:Divide by zero?

[toadlife]

Then you'll know how a person with severe OCD feels.

Re:Cool trick you can do with Deja Vu..

[j00r0m4nc3r]

Maybe he tattooed all those things he wanted to intentionally forget onto himself so he would know whether or not he actually forgot them after he forgot them.

I dont "see" anything

[Tweekster]

I feel the situation, sight has nothing to do with deja vu.

It's a remarkably stupid piece of research...

[jd]

...based on a remarkably stupid theory. I'm going to type this out slowly, so that the cognitive scientists out there can follow what I'm saying. Deja Vu may occur in any number of possible ways, but the human brain needs to be able to recognize ANY stimulus extremely quickly, for survival reasons. Vision, if anything, should be the least of the senses that gets such verification, because if you're looking at a threat directly, you probably don't need to remember that it was a threat the last time. It should be pretty obvious. Sound, smell, taste, touch -- these contain far less information to start with, so increasing the odds of a false positive, but need to be checked far more thoroughly because potential hazards can be much less obvious.

A false positive is bad, especially if there are far too many, but a false negative can be lethal. This would be more true, say, 100,000 years ago than today, and that's when most of these mechanisms became as finely tuned as they are. Back in the days when hominids were trudging through deadly terrain, you had to remember places and situations that were Bad News with enough time to get clear. In those days, there was a shortage of humvees, so having time to get clear meant having extremely early warning. From that, Deja Vu is a very obvious, direct consequence. In fact, no matter how good humans may have been at avoiding such situations, Deja Vu would always be selected for far more often than against.

(The above can be translated by crypto geeks as follows: The brain has a really crappy but very very fast hashing algorithm used to label sensory data. It's so fast that being crappy doesn't hurt survival chances, but it's crappy enough that we are seeing a very large number of hashing collisions.)

Now, here is where it gets fun. The senses are all cross-linked and cross-referenced in the brain. When the barriers in the brain don't work as expected, we get synaesthesia. Now, it is not at all obvious where the comparison is made, or how the barriers work. For this reason, it is entirely possible to imagine a situation where data from sense A is compared with a prior input from sense B. All it would take is for the barrier to fail to work correctly for recalled data, even if it worked just fine otherwise. This is not "classic" Deja Vu, because the brain is not incorrectly matching an experience with a prior experience of the same sense - it is incorrectly matching totally different types of data. Is this possible? Depends. Any connection that is bi-directional in the brain by nature can fail to mask or block data in either direction, so I can see absolutely no reason why - given synaesthetes are proof that the failure can occur one way - it cannot fail on recall.

(There are soooo many brain disorders associated with inexplicable associations, spooky feelings and false associations that you could fund half the field of neurology for the next fifty years just looking at sensory mismatches and nothing else. Given that, I'd call it almost a flat-out certainty that some of these experiences are cross-sensory errors that involve some of the same matching failures as Deja Vu.)