human eye refresh rate

[bobsmith1492]

Originally posted by: Born2bwire

Originally posted by: bobsmith1492
Yeah it looks like if Vsynch is on, the program is limited to either half of the screen refresh rate or full, and some areas where it is fully adjustable. If you turn off Vsynch, it's much more controllable (and runs up to 200 FPS!)

Also, the readme says it's made for 640x480 only.

LCD refresh rates are the rate at which the pixel positioning is updated, I'm pretty sure.

If I recall correctly, triple buffering will help with Vsync when it has to drop below the full refresh rate.

It's enabled on my machine. I'd hate to see it with it disabled! Maybe I'll try it anyway...

 

[gsellis]

Originally posted by: CTho9305

Originally posted by: gsellis
The human eye has a rate of about 30 frames per second. Anything faster and our brain fills in the gaps.

Interesting claim... download all the files in this directory, run the program, and let me know if you still feel the same way.

Ah, but there is a catch. You are talking running fps on an interlaced monitor with a refresh rate that is different. That is why lighting and the monitor at 60Hz create flicker. If I run a projector at 30 fps against a wall and then run it at 60 fps, it should not appear different to the human eye. Run a strob out of sync with it and you can find the framing.

BTW, that program has issues. Try this little experiment. Change the right side to 60 to match the left and they are different. Bump the left side to 30 and it looks awful. You are seeing the interlace skip being more pronounced from the look of it. Venetian Blinds effect. You see this a lot with 1080i HDV video or 480i video with a flash. So, maybe it is a good argument for running at least 45fps in a game, but not what the human eye can see.

PS - still stands that most humans see a 30 rotation per second pulsar as solid. Look at the Crab Nebula sometime and see if you see blinking

 

[xtknight]

Originally posted by: CycloWizard

Originally posted by: bobsmith1492
Ya, my refresh rate limits me to 60 (LCD) - maybe I can bump it up, though...

Somewhat unrelated question, but what does the refresh rate of an LCD really control?

Is it the frequency of the backlight?

No, usually the backlight is modulated at 200-350 Hz to control brightness. PWM I think they call it. I don't know, I'm not an EE, that's just what I've been reading on X-Bit Labs.

The backlight needs to be flickered to alter brightness but not to refresh the image. Newer LCDs will flicker the backlight to help remove an afterimage, much like CRTs. But there will be an option to disable that.

The pixel update rate?

The rate at which the crystals can twist to a specified color is called the response time (partly 'rise' and partly 'fall'). AFAIK all LCDs are synchronized to update at 56-64 Hz (typically 60 Hz). The DSP interpolates a higher refresh rate and downscales it to 60 Hz. Every 16.66 ms (1000/60), all of the transistors on the TFT are addressed with a voltage that causes the crystals (subpixels) to twist.

I wouldn't rely on those FPS applications. Refresh rate over DVI is really problematic. 60 Hz is actually 59.7 Hz on some LCDs (motion appears jerky). I need to send my LCD 60.3 Hz to get a 60 Hz, jerk-free image. Anything >60Hz on an LCD can't be accurately judged either. I suppose it will still look smoother though. An ideal config for testing FPS is a CRT hooked up with VGA, where both the video card and monitor truly support up to 100 Hz. It'll be fully analog so little imperfections won't cause weird jerkiness.

With CRTs, an electron starts from the top right and goes across the screen in a raster pattern, exciting all the phosphors on the screen. The intensity of the electrons(?) is varied as it goes across the screen which is how different shades are displayed. Technically, a CRT can display an infinite amount of colors, however most current implementations are limited to 256 shades per subpixel. When the phosphor is struck, it stays lit for about 1 ms and gradually decays, AFAIK. (Update: "decay to 10%" for the P22R phosphor is 850 µs).

I think the general consensus is that we can't distinguish frames above 60 fps, but we can tell that the motion is smoother. For example, a 120 Hz image sent to our '60 Hz' eyes will be blurred and smeary, which makes it look smoother. Maybe it's just a product of afterimage decay.

 

[CTho9305]

PS - still stands that most humans see a 30 rotation per second pulsar as solid. Look at the Crab Nebula sometime and see if you see blinking

On-off flashing is different from motion - persistence of vision of a stationary point will take care of flashing in the dark fairly well.

 

[glugglug]

If an image were only presented for less than a millisecond each frame, at 100fps, with a black screen the rest of each 1/100th of a second, every sighted person on the planet would notice.

Human perception is nowhere close to only 60Hz. The reason CRTs appear to have a solid image at 75Hz is that the image takes about 1/75th of a second to fade most of the way to black, so it's never really going away completely.

Also, that FPSCompare program lowers my refresh to 60Hz, which kind of defeats the purpose.

 

[CycloWizard]

Originally posted by: glugglug
If an image were only presented for less than a millisecond each frame, at 100fps, with a black screen the rest of each 1/100th of a second, every sighted person on the planet would notice.

This isn't necessarily true. It depends on the intensity of light relative to the baseline intensity that the particular photoreceptor(s) were fixed on prior to the flashing of the image. That, and sighted persons with low vision might not catch it.

 

[Gannon]

Actually I do not believe enough is really understood about the eye and brain to make any kind of assumptions that "the eye only see's" at 30 frames per second.

Certainly if you could speed up how fast a brain and nerves processes information you would then "slow down" time for that person.

There is evidence of this effect in children, when children are really young time seems to pass much slower for them because they are absorbing enormous amounts of information from their environment. As you get older time seems to pass much quicker.

I'm sure if we took someone who had slow processing speed and someone who had fast processing speed, their perceptions of time might be somewhat different.

 

[CycloWizard]

Originally posted by: Gannon
Actually I do not believe enough is really understood about the eye and brain to make any kind of assumptions that "the eye only see's" at 30 frames per second.

Certainly if you could speed up how fast a brain and nerves processes information you would then "slow down" time for that person.

HK Hartline won the Nobel Prize in Medicine for his work in phototransduction back in 1967 after working on it for about 45 years. I teach his preparation of the horseshoe crab eye to a biology class, so I've done some reading of the literature on the subject. The professor heading the lab did his PhD work on modeling the horseshoe crab's visual system and the brain's response (i.e. the visually-guided behavior) back in 1990. TVs and films were moved to 30 fps instead of 15 fps that they ran at previously to take advantage of this new understanding of photoreception and the flicker-fusion phenomenon. So I don't think it's necessarily correct to say that it's poorly understood when it's actually been studied for almost 100 years.

There is evidence of this effect in children, when children are really young time seems to pass much slower for them because they are absorbing enormous amounts of information from their environment. As you get older time seems to pass much quicker.

I'm sure if we took someone who had slow processing speed and someone who had fast processing speed, their perceptions of time might be somewhat different.

I'd question whether the perceived timescale of childhood is different because they're absorbing more information. I would suggest that the difference is really the relative experience basis, something like the perceived length of a year to you is, in arbitrary units, proportional to the reciprocal of your age. Of course, this is based solely on my own observations and wild speculation.

 

[Silx]

As for the refresh rate of a monitor, I can tell you anecdotally that, even in the absence of other light sources (i.e. only my monitor is turned on), I'll get a headache if I use a computer at 60 Hz for a prolonged period. I can also tell when gaming if my framerate starts to drop below 120 Hz. This is because the discrete signals going to my brain have fewer impulses and behave somehwat irregularly due to the 'chopiness' of the resulting signal. My brain has a hard time dealing with this irregular input and has to work harder to form an image.

This sums up my reactions too. Anything below 60hz flickers for me and gives me insane headaches. I cannot stand flourescent lights, because they flicker at the same rate. Some people think I'm crazy because I can see the difference between a screen running at 60hz, and a screen running at 70hz.

 

[Gannon]

Originally posted by: CycloWizard

HK Hartline won the Nobel Prize in Medicine for his work in phototransduction back in 1967 after working on it for about 45 years. I teach his preparation of the horseshoe crab eye to a biology class, so I've done some reading of the literature on the subject. The professor heading the lab did his PhD work on modeling the horseshoe crab's visual system and the brain's response (i.e. the visually-guided behavior) back in 1990. TVs and films were moved to 30 fps instead of 15 fps that they ran at previously to take advantage of this new understanding of photoreception and the flicker-fusion phenomenon. So I don't think it's necessarily correct to say that it's poorly understood when it's actually been studied for almost 100 years.

Tests with Air force pilots have shown, that they could identify the plane on a flashed picture that was flashed only for 1/220th of a second.

That is identifying. So it's pretty safe to say, that recognizing, that some light was there is possible with 1/300th of a second. Now if you take into consideration, that you have two eyes with different angles and different areas of sensitivity (you probably know, that you see TV flickering best, when you don't look directly into the TV screen, but with the sides of your eyes) and you can move/rotate/shake your head and your eyes to a different position, you probably needed flashes as short as 1/500th of second to make sure, nobody sees them in any case.

Also you should understand that scientific knowledge is largely based on QUALITY of the tools (coneptual, and technological... i.e. math, computers, telescopes, measuring devices, etc) to look at and study a system, you can study things for any amount of time but without the right tools to give you a CLEAR picture of what you are studying, you are studying the in dark and inefficiently.

Check out this article here.

http://www.100fps.com/how_many_frames_can_humans_see.htm

There are studies and information that tell us things that seem to contradict any kind of agreed upon uniform understanding at the moment.

Lastly as an anecdote you have people that can see much further because they have more or better cellular equipment in their eyes then other people, my vision is 20/15... in other words I can see better then people with 20/20 despite the fact that I am nearsighted... when my vision is corrected I have higher resolution visual perception at longer distances then other people witth "lesser" eyes.

I'd question whether the perceived timescale of childhood is different because they're absorbing more information. I would suggest that the difference is really the relative experience basis, something like the perceived length of a year to you is, in arbitrary units, proportional to the reciprocal of your age. Of course, this is based solely on my own observations and wild speculation.

First of all we know that the faster you can process information, your perception (i.e. samping rate, larger working memory or memory capacity) of time goes up so this would in effect may make time seem to pass slower, and/or there are most likely other systems involved with the perception of time as a child ages.

I think some anecdotal evidence is perfectly valid and is in fact evidence, it's just that it cannot yet understood or unable to be studied because the tools, conceptual and technological simply aren't there.

Science usually has to wait for tools to catch up with anecdotal evidence... human beings have a need to think they know "thinks very well" the truth is they don't most of the time, one only has to look at the state of the modern world to see how "enlightened" people are, even amongst the allegedly superior or "elite". Does not make one immune from mistakes, unless you're a god, you're still very very small minded in terms of how much information you can fit inside your head and process at any one given period of time.

 

[CycloWizard]

Originally posted by: Gannon
Tests with Air force pilots have shown, that they could identify the plane on a flashed picture that was flashed only for 1/220th of a second.

That is identifying. So it's pretty safe to say, that recognizing, that some light was there is possible with 1/300th of a second. Now if you take into consideration, that you have two eyes with different angles and different areas of sensitivity (you probably know, that you see TV flickering best, when you don't look directly into the TV screen, but with the sides of your eyes) and you can move/rotate/shake your head and your eyes to a different position, you probably needed flashes as short as 1/500th of second to make sure, nobody sees them in any case.

That's all well and good, but you totally ignored everything I said. I'm pretty sure I clearly stated that how much time is required to elicit a neural response depends on the intensity of the stimulus relative to the background intensity. I can prove this on an abacus. You're making arguments in the direction of object recognition, which I'm not nearly as familiar with and, as you'll notice, haven't even attempted to address. Object recognition is governed separately from simple phototransduction and has studied extensively in frog models. However, the bottom line pertaining to what you actually said
is that the neural response (i.e. did I see or not see a change in intensity?) depends on two factors:
1. degree of photopigment isomerization caused by light or dark adaptation and
2. intensity of the stimulus

Also you should understand that scientific knowledge is largely based on QUALITY of the tools (coneptual, and technological... i.e. math, computers, telescopes, measuring devices, etc) to look at and study a system, you can study things for any amount of time but without the right tools to give you a CLEAR picture of what you are studying, you are studying the in dark and inefficiently.

I'm pretty much aware of this. I've spent most of my time in grad school thus far developing new equipment to measure ridiculous and silly thing. As an engineer, I'm also vaguely familiar with the concept of mathematical modeling, which is what I do in my free time when I'm not building instruments. But you're probably right - I exist in a happy make-believe world of ignorance.

Lastly as an anecdote you have people that can see much further because they have more or better cellular equipment in their eyes then other people, my vision is 20/15... in other words I can see better then people with 20/20 despite the fact that I am nearsighted... when my vision is corrected I have higher resolution visual perception at longer distances then other people witth "lesser" eyes.

Suffice it to say that if you're truly myopic, you will not have 20/15 vision. Perhaps your best-spectacle-corrected Snellen visual acuity is 20/15, but not your native acuity certainly. You're confounding a lot of things here.

 

[Gannon]

Originally posted by: CycloWizard
That's all well and good, but you totally ignored everything I said.

There's good reason for that, Frog eyes are not human eyes. I googled HK Hartline and he won the nobel in 1967, he died in 1983, most of his work is old and while it has some cross over and some relevance, and yes he did find out important things. But there are still lots of things for us to find out. Science is a moving target. His contributions certainly isn't the be-all and end all of vision, after all the actual biochemical systems and the underlying molecular biology of the human eye were only able to be figured out much later then his studies, the actual equipment to do the investigative work necessary to piece it all together has been constantly evolving and even today is still not all there. The human visual system is still not completely understood. This is all I was saying, was 'leave mind open to new data' as advances in understanding of the complexity of living cells and their related structures evolve.

However, the bottom line pertaining to what you actually said
is that the neural response (i.e. did I see or not see a change in intensity?) depends on two factors:
1. degree of photopigment isomerization caused by light or dark adaptation and
2. intensity of the stimulus

In order to say that some function is understood, every relevant step in the process must be elucidated. The relevant steps in biological processes occur ultimately at the molecular level, so a satisfactory explanation of a biological phenomenon such as sight, or digestion, or immunity, must include a molecular explanation of the entire system.

"In contrast, molecular understanding of the (human) visual cycle is poorly developed, and many fundamental questions regarding reactions, enzymes, and control mechanisms remain unanswered." --- From the Departments of Ophthalmology and Biochemistry, University of Washington School of Medicine, Seattle, Washington. 2000

All I was saying was that our understanding of the human visual system is incomplete, I did not insinuate anything else.

Suffice it to say that if you're truly myopic, you will not have 20/15 vision. Perhaps your best-spectacle-corrected Snellen visual acuity is 20/15, but not your native acuity certainly. You're confounding a lot of things here.

The problem with my eyes is a matter of focus, it's not the entire visual system of my eyes, I can see things very clearly close to me without aid or glasses, with perfect clarity within about 5 feet, my focus has slowly worsened during my teens and slowed down to a stop in my 20's. I also had 20/15 when I was a kid, I didn't need glasses or contacts until I got to highschool, so obviously it wasn't always imperfect there was some problems that my eyes simply could not compensate for as the were growing in real-time and changing shape over-time. Lastly we have to remember our eyes are constantly doing mantenance while under operation, such as repair and garbage disposal of cellular waste, etc. Try fixing your engine engine going even 20 mph not a feat you can easily accomplish. Problems with the kind of advanced nanotechnology you find in human eyes is not to be unexpected. I'm certain as we develop our own artificially enhanced versions of eyes, we'll come to understand the difficulty and natural constraints that are constantly attacking the self-regulating , self-repairing system. Nature is a destroyer as much as it is a creator of things.

 

[CycloWizard]

Originally posted by: Gannon
There's good reason for that, Frog eyes are not human eyes. I googled HK Hartline and he won the nobel in 1967, he died in 1983, most of his work is old and while it has some cross over and some relevance, and yes he did find out important things. But there are still lots of things for us to find out. Science is a moving target. His contributions certainly isn't the be-all and end all of vision, after all the actual biochemical systems and the underlying molecular biology of the human eye were only able to be figured out much later then his studies, the actual equipment to do the investigative work necessary to piece it all together has been constantly evolving and even today is still not all there. The human visual system is still not completely understood. This is all I was saying, was 'leave mind open to new data' as advances in understanding of the complexity of living cells and their related structures evolve.

I didn't say they were the end-all, be-all. I simply stated that people have been looking at the neurological basis of vision for almost 100 years. Indeed, the study of our visual systems goes back to Descartes. I'm doing my PhD work on the human visual system based on the classical work of Descartes and Helmholtz. With modern technology, I can definitively prove some of the long-debated hypotheses that they set forth. The problem with your approach is that you think simply because new technology may come about at some time, things that we already know definitively will change. My mother once told me to keep an open mind, but not so open that everything falls out. I have read the literature and performed the experiments myself. I know as well as anyone that the human visual system is not fully understood. Otherwise, the 43 research PI's in our ophthalmology department would be out on the street. The problem is that you were not simply stating that we don't know everything. You were claiming that we don't know anything that applies to the OP, which is patently false.

In order to say that some function is understood, every relevant step in the process must be elucidated. The relevant steps in biological processes occur ultimately at the molecular level, so a satisfactory explanation of a biological phenomenon such as sight, or digestion, or immunity, must include a molecular explanation of the entire system.

The hell are you talking about? I can very well understand things without knowing every intricate detail of its operation. For example, I know how my car works in painstaking detail. I've taken it apart and rebuilt it more times than I'd care to count. But I can't tell you the design parameters (e.g. the combustion chamber temperature, air intake flowrate, spark plug voltages). Does this mean I don't understand how my car works?

All I was saying was that our understanding of the human visual system is incomplete, I did not insinuate anything else.

Liar.

The problem with my eyes is a matter of focus, it's not the entire visual system of my eyes, I can see things very clearly close to me without aid or glasses, with perfect clarity within about 5 feet, my focus has slowly worsened during my teens and slowed down to a stop in my 20's. I also had 20/15 when I was a kid, I didn't need glasses or contacts until I got to highschool, so obviously it wasn't always imperfect there was some problems that my eyes simply could not compensate for as the were growing in real-time and changing shape over-time. Lastly we have to remember our eyes are constantly doing mantenance while under operation, such as repair and garbage disposal of cellular waste, etc. Try fixing your engine engine going even 20 mph not a feat you can easily accomplish. Problems with the kind of advanced nanotechnology you find in human eyes is not to be unexpected. I'm certain as we develop our own artificially enhanced versions of eyes, we'll come to understand the difficulty and natural constraints that are constantly attacking the self-regulating , self-repairing system. Nature is a destroyer as much as it is a creator of things.

I can tell you exactly why you're nearsighted. Your cornea and lens changed as you aged, as did the axial length of your eye. Chances are, your cornea is too thick and/or too curved, resulting in an excess optical power. As a result, the light entering your eye is focused anterior to the retina. Your cornea changes very slowly after age 13 (when the entire eye stops growing) and nearly stops in your early 20's. Your lens continues to grow throughout life, which is why you'll eventually need reading glasses (called presbyopia). That you had 20/15 vision early in life does not mean you have 20/15 vision now. It simply means that you were fortunate enough to have a slightly better-shaped cornea at a young age than the average person (since the Snellen visual acuity system is based on the 'average' person by definition, hence 20/20 is the visual acuity of the average person at 20 feet. 20/15 means that you could see at 20 feet what the average person could only see at 15 feet). This doesn't have anything to do with enhanced neurological faculties. It has to do with optical systems. Every person (except low-vision persons) has about 125 million rods and some number of cones that I can't recall. These are reduced to about a million ganglion cells. The number varies some, but it has no perceivable effect on your visual acuity. Visual acuity in the human system is limited by the optics. You simply can't obtain a clear image from a blurry one, so if your optics aren't focusing correctly, you're SOL. I have about 20/350 vision (very nearsighted) and will be getting LASIK soon. I'll probably have 20/15 vision afterwards. LASIK is the reshaping of my cornea, not implantation of new rods and cones in my retina. /ramble

 

[fire400]

then what about typing on a keyboard? if I had to write down all the letters of a keyboard, I couldn't do it without looking at an actual one or maybe attemping to feel my way through an imaginary keyboard on my own.

however, I can still type without having to use my eyes to look at the keyboard?

what is the fps for what we can visual in our heads? the fps of our dreams when we imagine or when we are sleeping? -with respect to vision and comprehending detail of color and motion, the boundaries of any physics and the possibility of understanding perspective

but answer me this one, also? if a child notices the slower passing of time more, you guys mentioned that perhaps that child has so much to absorb compared to an adult? but doesn't it also depend on how much the child knows how to absorb in regards to priority or mental direction?

are there techniques in which we can adjust our brains to focus more on an aspect of human vision without squeezing our brains too hard?

 

[Smilin]

Originally posted by: Gannon

Originally posted by: CycloWizard
Tests with Air force pilots have shown, that they could identify the plane on a flashed picture that was flashed only for 1/220th of a second.

Do you have a link to that? I read this myself years ago when I was in the Navy (circa 1996) but it was hard-copy and I've never been able to find any web based links to the study. It was interesting stuff and I'd like to see it again.

 

[GalvanizedYankee]

Originally posted by: Smilin

Originally posted by: Gannon

Originally posted by: CycloWizard
Tests with Air force pilots have shown, that they could identify the plane on a flashed picture that was flashed only for 1/220th of a second.

Do you have a link to that? I read this myself years ago when I was in the Navy (circa 1996) but it was hard-copy and I've never been able to find any web based links to the study. It was interesting stuff and I'd like to see it again.

It's out there. Tests have shown that the very best F1 drivers and fighter pilots can get down to 1/300th of a second.
Someone linked the article during a discussion on frame rates in GH last year.


...Galvanized

 

[Fallen Kell]

Actually some people see more then 60 FPS. It can be calculated and tested by flashing images to a person and monitoring their brain activity. The person will not be able to consciously detect an image or message, but their subcouscious will, this is how subliminal messages work. By watching the person's brain scan, you can detect the point when their eye's detect the image/message. And you can then use this test in conjuntion with lowering the amount of time the image is displayed and find the point where that person actually can detect a change that their eyes see. Using the time the image is displayed you can calculate the "refresh rate" of the human eye on that person (i.e. if the image is no longer detected when only shown for .01 seconds, then the refresh rate is approx 100 Hz...)

 

[Gannon]

Originally posted by: CycloWizard
You were claiming that we don't know anything that applies to the OP, which is patently false.

Wrong, I claimed no such thing, you read that into the subtext yourself.

I've taken it apart and rebuilt it more times than I'd care to count. But I can't tell you the design parameters (e.g. the combustion chamber temperature, air intake flowrate, spark plug voltages). Does this mean I don't understand how my car works?

You're missing the point: Your car is a known quantity, people build cards... no one yes yet to build from scratch, grow in real-time 3D over many years, human eyes. Big difference.

You can know how some isolated part of a system functions or some simple system and not understand the functions in aggregate. And your car is a lot simpler then a human eye, we're talking huge orders of magnitude here. While you can understand some of the simpler systems of the eye, like I said before, the visual system is far from being completely understood on the molecular level from a systems and information processing perspective.

Liar.

You really need to tone down your evolutionary instinctual need for feel superior to others, you're engaging me with a hostile subtext.

I can tell you exactly why you're nearsighted. Your cornea and lens changed as you aged, as did the axial length of your eye. Chances are, your cornea is too thick and/or too curved, resulting in an excess optical power.

It doesn't take a genius to know that, especially when you're the one who has the eye problem.

That you had 20/15 vision early in life does not mean you have 20/15 vision now.

Correct, but I do have 20/15 vision NOW I just had my vision tested thank you very much.

Visual acuity in the human system is limited by the optics. You simply can't obtain a clear image from a blurry one, so if your optics aren't focusing correctly, you're SOL. I have about 20/350 vision (very nearsighted) and will be getting LASIK soon. I'll probably have 20/15 vision afterwards. LASIK is the reshaping of my cornea, not implantation of new rods and cones in my retina. /ramble

I understand, and my eye doctor told me I couldn't get lasik because one of my eyes is slightly misshappen. Although I can't say I've looked into the matter. My last eye doctor told me I could have lasik... so one of them has to be wrong.

 

[CycloWizard]

Originally posted by: Gannon
Wrong, I claimed no such thing, you read that into the subtext yourself.

You said, and I quote: "In order to say that some function is understood, every relevant step in the process must be elucidated. The relevant steps in biological processes occur ultimately at the molecular level, so a satisfactory explanation of a biological phenomenon such as sight, or digestion, or immunity, must include a molecular explanation of the entire system. " You even bolded that part yourself - I didn't add any emphasis.

You're missing the point: Your car is a known quantity, people build cards... no one yes yet to build from scratch, grow in real-time 3D over many years, human eyes. Big difference.

I understand very well how a car works, but I can't build one from scratch. People understand how eyes work, but they can't build one from scratch. One can understand something yet lack the ability to reproduce it from its basic components. Similarly, one can build something from scratch without really understanding how it works. You can really tell if we understand something if we can model it to the extent that we can reliably predict its response to a given set of stimuli using not mere correlations, but mechanistic models. The function of the eye has been very well modeled. So, though we might not be aware of every enzyme involved, I think it's pretty much incorrect to say that we don't understand how it works.

You can know how some isolated part of a system functions or some simple system and not understand the functions in aggregate. And your car is a lot simpler then a human eye, we're talking huge orders of magnitude here. While you can understand some of the simpler systems of the eye, like I said before, the visual system is far from being completely understood on the molecular level from a systems and information processing perspective.

How do you know? Based on your inane comment about frogs not being people, I can only assume that you don't know much about animal models and how they may be used to make implications about human systems. Rather than try to satisfy my "evolutionary instinctual need for feel superior to others", I'll point you in the direction of some papers that looked at these issues. Most of them are written about 40 years ago, starting with "What the Frog's Eye Tells the Frog's Brain" by Letvin et al., 1971, and the Nobel lectures by Hubel ("Evolution of ideas on the primary visual cortex, 1955-1978 : A biased historical account") and Wiesel ("The postnatal development of the visual cortex and the influence of environment") in 1981. I can give you more references if you want. I suggest these not to snowball you with information, but to demonstrate that people (not myself, but other people ) understand in gread detail how all of these things work.

You really need to tone down your evolutionary instinctual need for feel superior to others, you're engaging me with a hostile subtext.

You lied. I called you on it. I pointed out above where you contradicted what you're saying now. I don't have any need to feel superior, but I don't see why I should play patsy to placate you when you're spewing disinformation in my direction.

It doesn't take a genius to know that, especially when you're the one who has the eye problem.

Ooh, burn! Make fun of me for having bad eyesight. But I'm the one engaging you with a hostile subext in an effort to demonstrate my superiority as a result of my evolutionary need to feel superior to you, right?

Correct, but I do have 20/15 vision NOW I just had my vision tested thank you very much.

So you're not nearsighted? Good to hear.

I understand, and my eye doctor told me I couldn't get lasik because one of my eyes is slightly misshappen. Although I can't say I've looked into the matter. My last eye doctor told me I could have lasik... so one of them has to be wrong.

Are you talking to optometrists or ophthalmologists? This is definitely something that I would go to an ophthalmologist to discuss. Also, the reason for the discrepancy may also be time lapse between the two opinions. A plethora of research on LASIK and LASIK-related complications in the past 5-6 years has generated hordes of new guidelines for who is and who is not a good candidate for the surgery.

 

[Smilin]

I can pee further than all of you.

 

[Toastedlightly]

Originally posted by: Smilin
I can pee further than all of you.

back to OT with ye!

 

[Gannon]

Originally posted by: CycloWizard
You said, and I quote: "In order to say that some function is understood, every relevant step in the process must be elucidated. The relevant steps in biological processes occur ultimately at the molecular level, so a satisfactory explanation of a biological phenomenon such as sight, or digestion, or immunity, must include a molecular explanation of the entire system. " You even bolded that part yourself - I didn't add any emphasis.

And yes I used that to illustrate my OTHER comments which read ....

"There are studies and information that tell us things that contradict any kind of agreed upon uniform understanding at the moment."

Our understanding = incomplete, thats what I said in the first post.

Next I said,

"The human visual system is still not completely understood. This is all I was saying, was 'leave mind open to new data' as advances in understanding of the complexity of living cells and their related structures evolve."

Then I went to quote paper from 2000 which said : "In contrast, molecular understanding of the (human) visual cycle is poorly developed, and many fundamental questions regarding reactions, enzymes, and control mechanisms remain unanswered." --- From the Departments of Ophthalmology and Biochemistry, University of Washington School of Medicine, Seattle, Washington. 2000"

Then in my last sentence in that paragraph I said this:

"All I was saying was that our understanding of the human visual system is incomplete, I did not insinuate anything else."

I understand very well how a car works, but I can't build one from scratch. People understand how eyes work, but they can't build one from scratch. One can understand something yet lack the ability to reproduce it from its basic components. Similarly, one can build something from scratch without really understanding how it works. You can really tell if we understand something if we can model it to the extent that we can reliably predict its response to a given set of stimuli using not mere correlations, but mechanistic models. The function of the eye has been very well modeled. So, though we might not be aware of every enzyme involved, I think it's pretty much incorrect to say that we don't understand how it works.

I didn't say we don't understand how it works. I said our knowledge of how it works is incomplete, these are not the same things!

How do you know? Based on your inane comment about frogs not being people, I can only assume that you don't know much about animal models and how they may be used to make implications about human systems.

In nature, simpler versions of more advanced systems are structurally dissimilar in many ways. Thus, primitive eye-like structures in lower life forms are not scaled down versions of human eyes, but are totally different systems. Some functions will be the same but that doesn't mean animal eyes are like ours beyond the what is obvious and understood.

The big thing you are missing is that: While animal models are great, an immune system of a mouse is different from that of a human being, no sane scientist would think otherwise. There are differences and you have to be aware of them, one system is simply not a scaled down version of the other.

So you're not nearsighted? Good to hear.]

You're missing the point of course, is that my 20/15 corrected vision cannot simply be gained through correction alone. Say you have myopia or are nearsighted, then you get your vision corrected and your doctor says you have 20/20 vision when corrected. obviously the focusing power of my eyes are better then other peoples who have myopia when their vision is corrected. This is all I was saying: My corrected vision is 20/15.

I understand, and my eye doctor told me I couldn't get lasik because one of my eyes is slightly misshappen. Although I can't say I've looked into the matter. My last eye doctor told me I could have lasik... so one of them has to be wrong.

Are you talking to optometrists or ophthalmologists? This is definitely something that I would go to an ophthalmologist to discuss. Also, the reason for the discrepancy may also be time lapse between the two opinions. A plethora of research on LASIK and LASIK-related complications in the past 5-6 years has generated hordes of new guidelines for who is and who is not a good candidate for the surgery.

Well the big problem I'm worried if I ever consider lasik is about destabilizing my eyes ability to focus for long periods of time... not encurring "wobbling effects" when I'm trying to just focus normally on something due to corneal neovascularisation, which is the ingrowth of abnormal blood vessel into the cornea from the limbus (junction of cornea and eye-white). When I was younger I wore my contacts for extended periods of time unware at the time of oxygen deprivation to the cornea and its effect on blood vessel growth. But my optometrist caught it early then and I stopped wearing contacts and started wearing glasses for the most part, with me switching to contacts maybe half of the week.

I'm sure they have made great strides, I should probably go check it out again.

 

[beansbaxter]

can you overclock the eye's refresh rate naturally??

 

[DrZDO]

It causes me physical discomfort to stare at a 60Hz monitor, whether CRT or LCD, and I notice a faint flicker in bright regions. I don't know why this is. Naturally, I prefer something like 75Hz.

 

[Xdreamer]

This stuff is my area of study. I will attempt to explain this in laymans terms.

Point 1. assuming correct focus, the number and density of rods and cones are not the limit of visual accuity. there are colateral connections in the eye that allow perception of images that are smaller than the visual field of a single cell by allowing consensus between receptors. these same colateral connections act to exagerate definition thereby allowing rediculously sharp distinctions between objects.

Point 2. The eye is nothing compared to the complexity of the neuronal systems for visual perception. The occipital lobe (rear part of brain) is almost entirely deticated to conscious vision. We also have subconsious vison as mediated by the superior colliculus. (Have you ever ducked from something that you didnt actually see? There are some who are cortically blind who will duck from a thrown ball without any conscious knowlege that anything was thrown at them.)

Point 3. Rates of flicker fusion are different for differnt parts of the eye. In the center of the eye (fovea) flicker fusion actually drops to about 25 'fps' as it is specialized in high detail. in the corners of your eyes (peripheral vision) flicker fusion can be 60 or higher as it is more specialized for movement dectection.

Point 4. 1 'fps' from the eye contains not just current image information but information for context also. It contains the 'now', alittle bit of 'then', and alittle bit of the predicted future. Therefore, events are blended together and it alows the prediction of motions.

Point 5. Your brain is a fantastic pattern recognizer. Especially your visual system. It speeds up your vision to faster than real time. THe synaptic delays for the visual system indicate that the fastest consious visual response time should be .08 seconds. However, the actual reponse times are faster because your primary visual cortex is very good at predicting visual events and will report predicted events to your cortex based on previous information before the actual event information reaches it. This has been demonstrated in several expriements which have tricked the system and have created some very entertaining visual illusions. Anyway, insituations where the visual cortex predicted incorrectly, it edits your current perception to include the updated information resulting in a conscious experience that is actually a mishmash of predicted events and actuall events and is therefore inconsistant with actual reality.

Point 6. Object recognition (aka association between image and object identity) and sight are not the same. There are entire areas of your brain devoted to association. Association is a horrendeous ly complicated subject. Suffice it to say that there are certian things that you can recognize with very littel information (very tiny time periods of exposure) such as the face of your wife, or .... a spider. The amygdala is beleived to play a role in this (at least the emotional context thereof) and it has a 'first call' ability. ie. when you are shown an image of a spider (fear stimulus) you are scared before you consciously see the spider. For the navy pilots 1/250 sec exposure to an enemy fighter will clue them in to identity before the conscious response occurs.

I LOVE NEUROSCIENCE!!!!!!