What looks smooth at 12 Fps I had Doom 3 instilled when I had a virus and I knew amedenatly I was infected be of the slow speed. 12fps is unplayable in most cases.

 Edit: "automatically" *yawn* good night.

Just in case you were all wondering, the human eye can can see well over 200fps. Although it actually sees a constant stream of dynamic info rather than a preset number of analogue images, so the ultimate goal would be to create a display that doesn't refresh, but changes with natural fluidity.

Edit: Sorry if that seems like giberish, but it made sense to me as I was typing it.

all this human eye talk seems to say that no one knows why games run at 60fps.
I don't know either (really bad for somebody whody who is studying TV technology at uni, huh) but I would hazard a guess it would be down to TVs in most of the popular regions of games running at 60Hz...
I don't know I'll check it out to see if one of my textbooks has an answer

BTW I am definatley wrong with that theory as it refers to something completely different

*edit* p.s. the human eye can see well over 12fps. First off we percieve fluid motion at 18fps, but you would probably find it can see nearer 1000fps than 12fps

Ever looked at a CRT monitor with a scan rate of 60Hz? I don't know about you, but I end up wanting to stab my eyes out.

75Hz or higher and everything is cool.

CRT scan has an obnoxious flicker, so animation frames don't need to be as fast to look good, but sub-60 frames are noticeable for a lot of us. Things are pretty tolerable down to 30, but go much past that and your experience will suffer substantially.

I generally consider frame rate to be more important than any other visual attribute. If I'm not getting 30-60 frames, I'll reduce whatever settings I can to get it.

 I looked it up. NTSC was standardized to 60Hz because that's the frequency of AC power in the US. There are more details, but I'll let the curious look it up on Wikipedia for themselves.

The reason that movement looks smooth in films at 24fps is because of motion blur.

Motion blur can be added to games to make them appear smoother at lower framerates, but the blur requires additional processing power so it usually better just to increase framerate. It is fairly easy to notice the difference between a game running at 30fps and one at 60fps.

I'm not so sure about the human eye being able to see 200fps+ though. I have seen some studies that tried to prove the human eye could see high framerates, but the evidence was pretty shaky.

http://amo.net/NT/02-21-01FPS.html

 I was suprised this hadn't been mentioned yet. I pressed quote and then saw that you had just beaten me to it. On a side note, although movies are filmed at 24fps, the projectors often run at 48/72fps, duplicating the frames 2-3 times. This is because at 24fps, you will notice flicker.

In regards to why it is 50/60hz, I honestly thought it was common knowledge that its based of the mains frequency, hence why there is the difference between PAL and NTSC framerates.

Wow there is a lot of misinformation in this thread =P

Ok the first thing you need to understand is that your eye isn't the only thing involved in this process. Your brain plays an extremely vital role as well. In the real world things that move to quickly appear to blur. In most games up till now motion blur has not been around and the result is that you have crisp frames of animation that show up without motion blurring which makes the game appear jumpy and rigid. With this setup 60 FPS is required for most people to not see tons of jumping and sharp transitions etc..

Now when you add good motion blurring (I say "good" because bad motion blurring will hurt the matter) suddenly 30 FPS looks fluid and if you have excellent motion blurring like in a movie you can bring the FPS down to as low as 24 and practically nobody can tell the difference. This is part of the reason why 24 is standard (because its out of the range of perception for the vast majority of people due to the motion blurring captured on film).

Now where your brain comes in is in translating that blurring into fluidity of motion. Because it sees the information that the object(s) moved through space to get where they are it interprets that as a fluid movement, where as without the blurring it sees the object at one location and then suddenly another and it appears to have jumped.. So really the FPS situation boils down to a function not only have how rapidly your eye percieves changes but how those changes happen or specifically what it looks like while their changing.

Now supposedly, (I haven't seen this data/research personally but the story was one I heard from a professor) air force pilots have been able to identify an airplane that was flashed on a projector for only 1/200th of a second. But supposedly thats because of the way bright light will continue to effect your vision for a few seconds after exposure.

There is a lot on this subject that I don't feel comfortable speaking too, but I am reasonably certain that the data I have just typed is accurate as all of it was stuff I learned in a classroom setting.