How come when I take a picture of a computer screen...

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like I did once, with my camera, I could see all these stripes on the screen.

I asked someone what it was and they said it was the screen constantly refreshing itself.

What I wonder, is, how come we cant see these stripes with our eyes? It is weird, all the stuff that is going on on the screen, and when I look at it, all I can see is a sort of fuzziness over the top.

Our brains would see the stripes though, right? What effect does it have on our mind, to be looking at that for hours?

The camera has a shutter speed faster than the refresh rate of the monitor. If you could hold the camera still (or use a tripod) a long enough exposure would give you a complete image.

The human eye cannot see refresh rates faster than about 10 hertz, if I remember correctly.

If you just want a picture of what is on your screen just use the Print Screen button, commonly abbreviated at Prt Scr, it is usually the first button after F12.

You can't see the stripes because your eyes are too slow to see them. Nothing to worry about as long as you take breaks regularly.

Your camera can see the stripes (and show them to you), because it is faster than you. If you pump up the frequency (refresh rate) it will also be unable to see the stripes.

That's what they do in television series, and why you never see a 'striping' monitor while watching TV.

Isn't that strange? I see an effect like that sometimes when TVs are playing in movies or TV shows. But only sometimes. I have no idea why those lines appear on some TVs within movies and not others.

I have read that our brains are in a near-constant state of editing what our senses take in to make a seamless experience of the world. I have also read that people who have strong sensory difficulties with their autism have less of this editing going on and so a more sensorily accurate but less seamless experience of reality. (Or maybe that's just Simon Baron Cohen making stuff up. Hard to tell.) In any case, our brains just edit out the lines so we will not be distracted by them. Fascinating stuff. We would probably curl up in a little ball of sensory overload at all times if this filter wasn't in effect. Perhaps the people currently called "low functioning autists" are experiencing just that. (It's a thought. Might be an incorrect thought.)

You can sometimes see the partial image on a screen when you flick your eyes from side-to-side across the screen, or are looking at something else with the TV at the edge of vision. The edge of the retina is more sensitive to motion, while the centre has more detail. An even funnier effect is to eat something crisp, like potato chips, while looking straight at the screen.

A traditional* TV display will refresh a full image in about 1/30 second, made of two interlaced images each 1/60 second, so a slow shutter speed below 1/30 second should have a complete image. Anything faster will show missing portions, and 1/100 second will be half-black. (*traditional screens are being replaced by progressive-scan that shows complete, non-interlaced images with faster refresh).

That is because the technicians in some movies and TV shows know that they should alter the frequency of the TV set, so that they won't get the stripes. If you see stripes, it was probably low-budget.

Interesting replies! I am going out now so I will come back and comment.

Yeah. Our brains have to do an immense amount of processing to make sense of the images we get from our eyes. It's so difficult that we still don't really have computers that can do it - computer visual recognition tends to be either very specific, like going through a database of faces or numberplates, or it relies on simpler senses, like radar or laser ranging. There's no software that can take, say, a photograph of a room (or whatever - if you think about it, you could be shown a photo of anywhere on Earth and have a reasonable chance of working out what it was and what things were in it, and could recognise, say, a chair even if it was made in a style you'd never seen before, and so on) and identify the items in it, because to do so requires you know what things are and how they relate to each other... which takes us a long time to learn, and we never stop.
However, we don't, generally, blank things out. We aren't so stupid that (as is sometimes suggested) we "don't see things in front of our face because we don't understand them"; there are all sorts of tricks our brain pulls with our vision, like compensating for the blind spot and so on, but they're more the minor optical illusion sort of thing than "la la, I can't see that ship in the bay because I don't believe a canoe can be that big."

Ok, its funny because computers have a pretty strange effect on me and I dont know why.

Interesting idea. I find the worst problem i face is that my eye muscles cant keep up with looking at all the images on the screen, it is like they work slower than my mind takes in words.

For some reason, the computer screen I find, is very hard to read from. I have tried everything, from changing refresh rates, to coloured backgrounds.

I have the same problem with books and TV, but to a far smaller extent. I think the problem I have is I have fine motor dyspraxia, and it effects the way I coordinate my eye muscles.

This is completely false, I know for a fact that the average human eye could see at least 24-30hz. I can see over 60hz and therefore I won't use a computer with less than 72hz.

If you can see faster than 60Hz, you must live in a cave because all the lights in your house are turning off and on at 60Hz and I would imagine that it would drive a person insane.

As I remember from biology lessons years ago, the human eye refreshes at around 50 Hz. So we only see flicker in things that refresh slower than that. Hence monitors are designed to refresh at a minimum of around 60 Hz.

Then I would suggest not leaving the country. Most of Europe, I believe runs on 50Hz.

I think the human eye runs slightly less than 30Hz.

That's why motion pictures run at 30 frames per second. It is the minimum needed to produce smooth motion to the human eye.

I can see the computer screen flashing, it gives me a headache almost instantly. I also don't stare at light bulbs. Keep denying it all you will. Take me to a school computer lab, set half the displays to 60hz and half to 72hz I will pick out every single 60hz display without effort.