h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Ok so what is it that determines the colour we see when we close our eyes?...it seems to be different for different people (ive been conducting a bit of a survey for about 10 years), is it determined by mood, blood pressure, what colour you were just looking at, how tired you are, what you last ate? what do you think?
Can you make it change if you concentrate? (I just a mental picutre of a whole bunch of people sitting at their computers with their eyes closed, being accused of sleeping on the job...)

Pale mauve with yellow. I think it depends on 1) how much light there is the other side of your eyelids (lots here -it's a bright sunny day) 2) What you were just looking at (out the window at a blue sky with a few fluffy clouds) I can change the backdrop by conscious thought, but not the foreground.
BTW I remember very fierce reds and purples just before going under a general anaesthetic

It's a neon lazer lemon yellow type thing, with lots of bright flashing dots, and when I turn my head left to a dark area it becomes red, must be the blood flowing through my eylids or the light, you cloud be right

Pale mauve with yellow, thats one I haven't heard before..... most people are black with something, or white with something, or stars and stuff.....hmmmm... the quest for an answer continues...

Mainly brown, and octarine (which is a sort of greenish purple). I didn't believe octarine was a real colour until I noticed that it is one of the ones behind my eyes.

If I look through my closed eyelids at the sunshine, then I get orange, with red lines, which is clearly the colour of my eyelids, not the colour behind them.

Nice question - I didn't know different people saw different things.

It is quite interesting as lots of people see different things. I have so far worked out that the sun obviously makes a difference and the brightness of the day conributes a certain amount, but the underlying colours are often quite different.

I have come accross two people who see olive green, and two who see dark blue. There are quite a few who see varying shades of blue, including me, maybe it is an indicator of personality type and i draw 'blue' people to me????????

other than that, ive not noticed anyone seeing the same colours, and only some people seem to be able to change the colour if they concentrate. i think this comes with practice.

i still dont have any 'data' on whether it changes with mood cos i keep forgetting to check - perhaps i should keep a diary...

I just seem to have a random kalidascope effect ?

Ive heard that one before Happy...but what colours are in the kaleidescope? Sometimes it takes concetration to even realise that you are seeing any colours at all, which begs the question - are we just imaginaing all of them?, but even then, it still tells us something - it tells us the first colour your imagination comes up with - who kows what that means - but its got to mean something surely!!

The background is almost black, if it was day light here it would be burgandy, there are kelideascopic lightening flashe accross the eye, the colours are essentaly primary ones.

The human eye (and, by balance of probability most animal eyes) is actually an extremely poor bit of kit. The concentration of receptors is not constant across the retina and the blood vesels and nerves actually run _on top of_ the light sensitive surface. Also the colour receptors actually react much slower than the light intensity receptors. (Cones vs. Rods for the biologists out there).

What this means is that there is a pretty intensive bit of error correction continually going on in order to make any sense at all of this highly corrupt information stream. Of course, as with all error correction systems, it can't cope particularily well with sudden changes (which is why rapid change is actually blurred, and why stop frame animation, TV and movies work) or suddenly being deprived of information when it goes dark quickly or when you close your eyes.

At the point of closing your eyes you have the information still being processed (your pre-image), the ongoing information (the redness of your eyelid) and random error caused by your error correction losing its reference points (which is often manifest as little spots of multiple colours). The sum of this will be what you "see with your eyes closed".

Any counter theory anyone?
<>====uuu====<

a good theory Duncan, but why is everyones different (Ive only come accross two people with the same response, even when I ask two or three people all looking at the same thing - in about 6 years of asking people, thats TWO altogether from 6 years of research)

i think your theory has merit and is the most scientific ive heard as yet (Im a scientist - reproductive biology incase you're intersted) but i still dont think it explains it all.... i still think there is an element of imagination, or personality in there and i think that someone with more of an esoteric mind than mine, might even be able to some up with a way of 'reading' someones eyelids (!!!!!!) and determining something about personality or mood or future or something. ive noticed that i have surrounded myself with lots of people who see varying shade of blue (having asked hundreds of people, i realise that the ones that are closest to me or whose company i most enjoy are 'blue' people). and i find this Odd to say the least.

(escuse the typing it is extremely late at night and I should be getting beauty sleep, if only i could drag myself away from this!!!!)

Hi,
I am in a very dark room late at night possibly also tired like you, and I see deep purple with lighter almost grey line shapes, that move as I move my head. But then again, it could be just tiredness.

Moondancer

See, yet another response - still no two alike (other than once)

that didn't make sense did it????

I know what I mean anyway and i guess thats the main point

what I was trying to say was I have only ever heard two responses the same, other than that, everyone seems to be quite different....
its so wierd and has had me intrigued for years....

When I go into absolute darkness (i.e. put on a blindfold) I see ripple effects of grey on a dark purple or black background and they fade away over about 1 minute top complete black with just a sprinkle of purple or blue points which fade as quickly as they appear.

Thats a cool one.....
now can you make it change if you concentrate?
tomorrow, at random times during the day, close your eyes and check if its the same or different (putting your hand over your eyes like a blind-fold, but not pressing so as to distort any image) throughout the day..... I always forget to notice

but i do like the thought that out there, the world over, there are people who have started wondering about it too - its a great excuse when you get caught napping at work or in a class or seomthing - no sir/madam, I was just checking what colour is behind my eyelids!!!!

Where are you Duncan - what time zone?
its way past my bedtime here (Melbourne, Australia) Ive made a deal with myself - 25 more mintues then off to bed (that'll make it about 2am!!)

[15:39 GMT - Dublin, Ireland]
I nearly always have the same patterns, and if I open my eyes very quickly whilst the grey pattern is moving it persists over the "open eye" image.

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I was taught that it was just a combination of the neurological equivalent of white noise (from the neurons in the eye & optic nerve) combined with a bit of filling in from the brain's visual centres (hence the pretty patterns). I personally think its some kind of magic or something.

If you close your eyes and apply pressure to them with your thumbs, things can get pretty psychadelic, with lots of pretty patterns and stuff. If you do it for a couple of minutes, everything takes on a sort of washed out look, which is more orange than anything else. I think that this is something to do with the fact that you've just knackered (albeit temporarily) your rods and cones, and they don't have enough rhodopsin (the purple pigment that is essential for converting the light to nerve impulses) in them. This is just a theory though. Give it a try and say what you see!

- Adam

There's a first - a doctor advising you to stick your fingers in your eyes.

"White noise" is actually caused by background radiation in the radio wave part of the spectrum. It is not impossible that an altogether more feared type of radiation might cause the human equivalent? Certainly ionising radiation might explain my quickly appearing and dissapearing purple blue spots...and I'm only a short sea trip from Sellafield.

Since I first read this question, I've checked in different lighting conditions at various times of day and I only ever see black with a vague overlay of fuzzy yellow dots. I'd no idea other people saw fancy colours.