The link Yushire provided was someone who was well informed on the medical side of the fence but not so well informed (or possibly out of date) on the technological side of things.

Motion Blur - When the author said it would be a waste to implement motion blur in games they were flat out wrong. Their reasoning given was that objects would have no position since they would be blurred but this is a fundamental lack of understanding of the way a game actually works.

Conceptually a game is literally nothing more than big list of numbers (ie variables) which are translated by the hardware from frame to frame into a picture of what is happening. What is drawn doesn't impact the list of variables it is merely based on that list. So you can have a box at position (30,40,10) (ie an ordered triplet of (x,y,z))and draw it with a motion blur coming from the direction of (20,40,10). As far as the computer is concerned the box is at location (30,40,10) and any possible collision is based on that location alone...but when the frame is drawn it appears blurred...there is no problem for a computer here.

Yushire's first link with the video illustrates this well with the ball that has motion blur at 24 FPS looking identical to the 60 FPS.

USAF Pilots - This is a study I am familiar with (and I actually posted about it back in late January in the topic "Why is is so important games run at 60fps?". What the author of the article is saying about the implications of the study are extremely misleading. In the test pilots were seated in a pitch black room and a plane was flashed from a projector and they were asked to identify the aircraft based on what they saw. It is important to know that with aircraft identification you are looking at the shape and outline of the craft and specific detail is not required.

Now the author did mention correctly that they were able to identify the plane due to the afterimage which is truly what is important here. The rods of the eye are overexposed in this situation because th subject has been sitting in pitch blackness. The afterimage is "burned" into the eyes of the pilot allowing them a prolonged look at the shape of the craft and allowing them to identify it.

There is no evidence to suggest that when our eyes are not overexposed (as they usually are not) to the extreme we could perceive things with that little time to view an image and the lack of supporting evidence is not for a lack of trying.

In effect the minimum amount of time for you to notice something new in your vision depends largely on how much your viewing subject appears to have changed. In the case of the pilot it is the starkest transition possible (ie pitch black to bright light) and far from the actual conditions of how you use your eyes on a daily basis or while gaming for that matter.

Video Games - While movies use the standard 24 FPS they have the benefit of very good motion blur..complements of the serendipitous way cameras work as the article Yushire linked to explains. But like everything in our world this effect can be explained mathematically and that is how motion blur is implemented into a game properly. This article is actually a bit old as I'm sure many of you noticed and games have now been implementing motion blurring for a few years with good results...granted some poorly implemented attempts will look horrible but when done right it looks very smooth even at lower frame rates.

Other information - There is a study that has been shown on the science channel several times now that talks about the human perception of time and whether or not time slows down for you when under stress. The way they tested this was to give folks a wristband with a numerical display meant to show the wearer numbers like the following:

When the device was activated it displayed a random double digit number (such as 42) but it did so by alternating between the contrasts. I put together an example of what I am talking about so everyone follows. The alternating rate varied by subject from 22-28 swaps per second with the vast majority of people seeing a completely solid unflickering block at or before 24. In all cases the subjects had their setting dialed up to a solid block before the test.

The subjects were then lifted several hundred feet into the air and dropped into a net, while falling they were asked to attempt to read the display and most of the subjects were routinely able to get the first number (of the two digits) correct and often chose a very similar looking number for the second digit. Note that even with the added perceptual boost of adrenaline which boosts their rate of perception they still had a tough time making out the numbers.

That is best example of real world conditions being tested that I'm aware of and under all such real world conditions the human eye is strictly limited to the mid to high 20's.

We have to be careful because in many instances the author of this article is discussing the theoretical limit to what a human can perceive while we are discussing real world conditions that are present for the playing of a video game. The theoretical max as I mentioned in the best case scenario of high contrasting from black to white was 1/220th of a second (at least that is the best demonstrated so far). This is quite impressive but it is a best case scenario.

The real test of value however is the eye's ability to detect detailed changes in high speed and as I've said there is nothing to support the claims of infinity that this author suggest and in fact quite a bit to suggest the opposite.

I question the intentions of the author - I wanted to point out why I think that the author either doesn't fully understand or is misleading the reader with his article. In both parts of the article he asks for the reader to consider how the real world appears more detailed and precise than what you see on your monitor. The problem of course with this request is that it does nothing to prove a deficiency with the frame rate of your monitor or television, its actually a problem with the color range available and the restrictions of resolutions.

I don't understand how someone who says they worked closely with this technology could not understand this difference and not understand that frame rate would have nothing to do with this lack of vivid color and detail. Make of that what you will.

So sqrl how many frames can human really perceived? Its possible without headaches in 60 fps, there are games that have 120 fps again, without headaches. so what could all these mean? Atleast the author of the article debunked the 24 fps myth. BTW, I just seen the 60 hertz thing in a windows 95 monitor before in our PC, the refreshes was noticeable it gives me a headache after awhile.

And yeah, if sc94597 didnt read my last post, I noticed it on LAN since we have more than one PC, even kids noticed it. Thats how noticeable the 30 fps in 60 fps, and yeah, saying it isnt noticeable was blind or have different brains than in humans. We see with our eyes, we perceive with our brain.

And yeah, sc whats your specs? in your last post you said you have 30 fps in Crysis is that even possible? Crysis was a demanding game...

Yeah I read the post. I still don't think I notice  it running slow unless I see it side by side.

I have 3gb of ddr2 ram clocked at 333mhz

A pentium dual core e2140 overclocked to 3.0ghz for my cpu

A 512mb 8800gts for my gpu. I may have overclocked it I don't remember.

 It runs it at most settings on high and some at very high with DX10 at a constant 30fps. I might get another 8800gts and so I could see if I could run it at ultra high or just all settings very high.

I'd hate to see the game running at 60fps if the pics at IGN are from a build of the game that is aiming for 30fps.

@sc----> LOL believe me, theres a difference, thats why Im into this framerate thing. If theres a new thing you get used to you cannot turn back.

About your specs, WOW and Im only half of those specs and its still in 30 fps?!! Crysis was too high end even for us gamers.

 What are your specs? I'm pretty sure you could run it on low settings. 

Same old troll, but fails as always, this time failed real hard.

There really isn't a flat number. Perception is a funny thing in that what one person perceives may not be what another one perceives, and not just in the sense that people can remember things differently. Part of the problem here is the definition of "perceive", we can certainly detect that something is wrong or notice that an image is jerky/jumpy when the frame rate is low and there is no motion blurring. This is something every gamer is familiar with when a game has frame rates that vary wildly and/or low frame rates and/or poor or no motion blurring.

If you want to take a strict definition of "perceive" and say noticing any change at all is perceiving then sure in the most extreme example the contrast from pitch blackness to light shows we can notice a change in at least 1/220th of a second.

In a practical setting the entire field of vision is not going from pitch black to bright light so the changes are far more subtle and what people perceive varies quite a bit from person to person. Part of the issue is that while your eye gets all of the "updates" of information your brain doesn't necessarily have to process it all.

In truth the reason explaining vision in terms of FPS has so many problems is because the author of article is correct that it doesn't really work that way. FPS is just an approximation for how quickly we notice changes. Yes the eye and the brain constantly receive information but the speed with which it is processed and the brain's ability to detect actual changes within that constant feed of info are what actually effect your perception of the world ( or in this case the gaming world).

In cases where there is a great deal of of change from frame to frame at 30 frames per second it will be noticeable to the viewer, which is why motion blur can reduce the problem dramatically. But in cases with little or no change its not noticeable.

The bottom line is that what you're viewing has everything to do with how smooth it looks. Games with high frame rates will look smooth, as will games with steady frame rates (ie a frame rate that doesn't spike up or down), additionally games with good motion blurring will look smooth as well. If you have a low frame rate and nothing to compensate for it then yes side by side with a 60 FPS game there will be something noticeably "off" about it, but even then without a direct comparison 30 FPS is still fairly smooth to the common observer.

The article didn't really debunk the idea that 24 FPS can be sufficient. If you mistate the position as "people cannot notice anything beyond 24 FPS" then yes, that is absolutely false, there are plenty of scenarios where you can notice jerky animation from 24 FPS. But properly stated the position is "people cannot notice change when excellent motion blurring is employed on 24 FPS film". The exception to this of course would be if the film contained frames that alternated from black to white...that would be very noticeable but it would also nullify the motion blurring anyways.

My overall point is that a frame rate below 60 can look perfectly normal depending on how its done. Above 60 is just icing on the cake and will look perfectly normal in almost all situations with the exception of the most extreme contrasting situations.

@SC- My specs sorry if it takes too long someone using the PC:

1 GB RAM
2.4 GHZ Pentium D dual core
Nvidia GEFORCE 7300/7200 GS 512 MB

Anyway, I can only have COD 4 30 fps on this spec, if its possible to play Crysis here let me know.

@sqrl----> So does it mean gamers especially a professional gamer have better perception than a ordinary people?

Not necessarily. Just the fact that they are looking at it far more often means that they pick up on subtle things and notice it more easily.

For instance we could do an experiment:

Day 1 - You are taken to a room with 60 random people and are given 5 minutes to remember their faces.

Day 2 - One of those 60 people from Day 1 is added to a group of 59 new people and you are asked to pick out which one person you saw the day before.

Most likely you wouldn't be able to do it where as someone who was friends with all 60 people from day 1 would instantly recognize their friend and get it right every time. Being familiar with an object or person means you will recognize more details about it but not necessarily that you are more perceptive than anyone else.

The gamers who notice these differences are primarly gamers playing games with poor or no motion blur at sub-60 FPS rates, especially fast paced games like Unreal Tournament etc..

edit: PS - To be perfectly clear I only have minor issues with the substance of what the author of that article wrote, his conclusion is where my biggest problem is at but I think that may have been a function of the article being somewhat outdated.