of course, the moment you say that, i notice my blinking. Then I think about the other involontary motions we never notice, like breathing. but now that I've noticed, i have to control it...and I do a worse job than if i left it well enough alone.

Gahh!

Lets see if this works: Who yawns after reading this (or feels like yawning?).

Thanks alot, now I need to get my mind off of what my body's doing. (pant, pant, blink, pant, huff, yawn, pant, blink...)

I noticed something interesting several years ago when I was trying to identify some of the Mexican music tunes in “Treasure of the Sierra Madre”. After some practice, I was able to mentally tune out the loud dialogue of the film and concentrate on the background singing. Now I can do either, tune out the music and listen to the dialogue, or tune out the dialogue and listen to the music. But I have trouble now listening to both the dialogue and the background music at the same time, as I originally heard them together the first dozen or so times I saw the film.

Stifled a yawn after I read that Rici! hehehe

All,
returning to the original theme, I see another ?allied? phenomenon on my TV. It is positioned so that walking by the room, I can see the screen through a slit between the open door and the door frame. Walking by, or standing still and moving my head, I can see vertical black lines on the screen, that are either truly vertical or sloped, according to how fast the eye is moving, side to side.

Try it yourself! How does this happen? The lines painted on the screen by the electron beam are horizontal.

John

I like this idea, that's where my money is. There's a natural frequency at which your eye moves back to the original location as you watch a propeller. I would think that persistence of vision would be a gradual rather than sudden fading, so it would be harder to pick out a specific frequency, but maybe that could work too.

I searched internet and didn't find any video example of this effect (reverse rotating wheel). Does anybody know where I could find it?

On the freeway when you're driving next to a big truck. Or when the light turns green and the car next to you is accelerating faster (or slower) than you.

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I've seen things you people wouldn't believe. Attack ships on fire off the shoulder of Orion. I watched c-beams glitter in the dark near the Tanhauser Gate. All those … moments will be lost … in time … like tears … in rain. Time … to die.

I think this is a wonderful hypothesis, and my initial feeling was that it's true. There's one doubt I have, though. The sample may be too small, but I turned on a fan in my office and asked fellow workers whether they saw the same effect. And they all did. But the thing I wonder is, if the effect is a natural speed at which the eye moves, wouldn't that speed vary from person to person, depending on their age or muscle strength, for example? Why would all humans move their eyes at the same speed? Maybe they do, and there's some reason for it. But I would recommend that other people try spinning something until you see it go backwards, and then ask people around you whether they see the effect at the same speed or not.

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As above, so below

Fluorescent lights (which strobe) or incandescent lighting?

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0 1 1 0 1 0 0 1 1 0 0 1 0 1 1 0 1 0 0 1 0 1 1 0 0 1 1 0 1 0 0 1 1 0 0 1 0 1 1 0 0 1 1 0 1 0 0 1 0 1 1 0 1 0 0 1 1 0 0 1 0 1 1 0....

Important question, you always have to watch out for the light source. Best is to turn off the fluorescent lights and use daylight or light bulbs. I remember seeing some interesting effects for propeller planes starting up, in broad daylight, but now I can't remember exactly what I saw. Can anyone describe an effect of this type they've seen in daylight? Jens' point is interesting, you might not expect everyone to see the same thing at the same time if it was physiological.

We've all seen it.
It is not exclusive to video, or film, or any kind of recorded medium.
When you are on the freeway looking at the cars going by, sometimes the wheels can indeed "look" as though they are going backwards.

There have been plenty of explanations typed up on the "retro-grade" effect we see when this happens on film. Basically, if a wheel is filmed at 24 frames per second, and it is also spinning at that exact speed, it will "go recorded" as if it were still.

Some might say that the wheel in the recording "is" still. After all, every 1/24th of a second, we see the exact same picture of the wheel.

This happens in other mediums as well.
Sound:
It has been observed that different animals all have different sensitivities to different areas of the sound spectrum. As we can imagine, cats seem to tend toward being very good at hearing high-pitched sounds, say, those made by a mouse rustling across a leaf. etc. the main idea being that it is a trait that usually can be connected with survival...go figure, Darwin.

At any rate (excuse the pun), Humans generally hear best within the range of 500-5000 Hertz, but as we go away from that range, things begin to get quieter and quieter until we just can't hear them at all. This, they say, in general is 20-20,000 (vibrations measured in units invented and named after a guy called Hertz)

But if you notice, CD digital recordings are done at a bit over 40,000 vibrations (44.1khz actually). Why?

Well if you record a tone that goes on and off (so to speak, they are really just peaks of vibrations) but you only capture the parts when it is "on", what you end up hearing on the recording is very similar the wheel "being" still on the film. What you hear is a "constant" tone. This can be heard in poor quality digital Mp3's etc as little high pitched "tin can" tones and sounds morphing and changing in the background of music, so to speak.

The reason we sample at twice the rate of what the human can actually hear is to account for this. Just as if we recorded the wheel at twice the frame rate, we would have twice as much recorded on film, of what the original situation "really" was.

But let's go back to the situation of seeing it with our bare eyes. What are we seeing?
Through inference we believe that the wheel is in fact turning. But our perception mechanism tells us that it is still.

It makes me think of black holes.
Here is a situation where we know we can't see something.(knowledge of no-knowledge) It is a limitation of our own perception. We see light from stars behind the black hole disappear as the go behind it and then as they come out the other side of the black hole, the light reappears.

All of this seeks to question the nature of the reality we perceive vs. a human-invented (and assumed) story-term called actual "reality"....which, according to definition, we have NEVER received, unfiltered by the former.

My question is, since we can only have perceptions in this world through our individual perception mechanisms, what are WE doing?


What if you could speed up your frame rate? To see into the gaps of time in-between what everyone else were seeing. would you?
What if you saw something that only blinked "on" at a rate that just always happened to be when all humans perceptions were "blinked off"? (or the parts that humans noticed were culturally rejected as "uncontrollable", "mystery" or "random"). If you told people, what would they say? better yet, What would they hear? how could you tell them?

A light bulb is actually a fast flicker, so fast, we don't see the "off" blinks.

What we are talking about here is what I'd call "other dimensions" that, unbenounced to us, could exist, (in my mind, naturally-MUST-exist) at the same time and in the same space as our "proper reality".

Past that, I don't believe that science in it's communal-aspect can study this much further. It becomes what some people call Quantum. (others call miscommunication).

Yet to study this for one's self becomes a spiritual journey where it's an entire world anew to explore without any history.

It begs the question: Does it exist if we don't notice it?

I recently almost died. In fact, I was so close that I had to psychologically accept it.....as "reality". The world was,( at least as far as I would be concerned), as I had known it. I would be getting nothing new from my perception-mechanism. During that "time" it seemed to me that my whole life was simply one "blink-on" of the light. One frame.

It turned out that the "reality" of the situation was not as I had perceived (haha the irony). I live on, and think about that wheel and it's recording.

My best goes out to you all for what it's worth.
Hope all is "really" well.

Welcome to the forum Ehmie, we are glad you didn't die! As for the issue of "what is real" and "what is time", the attitude normally taken here is that the words are so general that one could take a philosophical or poetic or any kind of "take" on them, but here we use the scientific take. So if we want to understand time, we need to ask how to measure it. I would submit that the "snapshot" of a life you refer to can be measured with two clocks, one embedded in the memory that recorded each "tick" of your life, and the one that was ticking while you were conceptualizing that life. The former clock had millions of ticks, but the latter one was just a fraction of a tick, into which all those former ticks were compressed. This is a lot like relativity, where any number of ticks on one clock can be compressed into a single tick of another clock. It's all a matter of reference frame. But the concept of "reality" survives in the way we know how to transform between the frames-- we know (some do anyway) how considering a whole life in an instant will appear to turn it into a snapshot, or how looking at a turning wheel with a given frame rate will make it look stationary. In other words, we have gone one better than "seeing is believing".

Hi all,

Something I noticed years ago learning to play the bass: If you pluck a string and look at it with a TV in the background, you see sine waves. Pretty neat. BTW, this also works with the guitar but the effect is more noticeable with lower tones.

I told myself that one day I would figure to tune the instrument using this phenomenon...sigh...never did.

cheers

Floresent tubes drop to about half brightness 120 times per second. About half brightness for USA television, but 60 times per second. Computer screens, and compact floresents lights have refresh rates up to about 200 times per second, so all behave like a strobe. persistance of the phosphor (and some other factors) detemines how close to black you get when the voltage crosses zero. The incandesent bulb filliment only cools a few degrees during the near zero voltage millisecond, so the strobe effect of an incandecent is negligible, unless the power is considerably less than 50 or 60 hertz which is standard, except many airplanes use 400 hertz to reduce the weight.
I have not personally observed the eye sample rate perhaps because my left eye vision is poor. Neil

CFLs usually have electronic ballasts these days. So do modern tube installations:

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I have a small 4W "night light" in my bathroom that is controlled by a photocell such that it only comes on at night. This light definately exhibits a stroboscopic effect. I suspect that the electronics in the photocell-control include half-wave rectifiers that result a more pronounced flicker.

That said, none of the other incandescent bulbs in my house exhibit flicker.

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Actually no, the eye and brain do not work in this manner. This is one of the most common misconceptions spread about, somehow pegged to fact that NTSC and PAL standards have both low framerates.

The human eye is capable of detecting extremely short bursts of light (fractions of a second), as studies have shown, and can distinguish minute changes in high frequency environments.

For example, you will definitely notice a difference in moving images involving a CRT monitor with a 60Hz refresh rate (updates 60 times per second) compared to a CRT monitor with 100Hz refresh rate, or an LCD monitor with a 2-4ms response time compared to an LCD monitor with 16ms response time.

The PAL/NTSC framerates are low, but can seem fluid due to motion blur. This is where the eyes "have a 24-30 FPS limit" misconception typically derives from. A good experiment to bash this misconception is to play a PAL/NTSC movie side by side on two LCD monitors, one with a 60Hz refresh rate (typical for most early LCD's) and the other with 120hz refresh rate (new models). Both movies are at 24fps (assuming NTSC), but your eyes will definitely pick up less motion blur on the 120Hz screen.

I'm not sure that's a good explanation of that test. You'd actually be testing the ability of the LCD to change its pixels quickly, and what you'd see are pixels in transition, not one image followed by another distinct image 24 times per second.

Two LCDs both at 60 Hz could have very different amounts of this kind of motion blur. Or, put another way, one screen capable of multiple refresh rates will have the same amount of this blur no matter its refresh rate. 24 FPS material played at 24 Hz will look identical to the same material played at 120 Hz. There is no difference between a frame held on the screen for 1/24th second and the same frame refreshed 5 times in 1/24th second, since nothing is actually changing in those refreshes. The response time of the LCD is only a factor when you go to the next frame, and that will happen 24 times a second, regardless of refresh rate.

EricM407, you might be right about that, mainly because I don't know enough about the decay physics of L