it really doesn't. I'm not explaining this a 3rd time. Just read.
The human visual system does not see in terms of frames; it works with a continuous flow of light information. A related question is, “how many frames per second are needed for an observer to not see artifacts?” However, this question also does not have a single straight-forward answer. If the image switches between black and white each frame, the image appears to flicker at frame rates slower than 30 FPS (interlaced). In other words, the flicker fusion point, where the eyes see gray instead of flickering tends to be around 60 FPS (inconsistent). However, fast moving objects may require higher frame rates to avoid judder (non-smooth, linear motion) artifacts — and the retinal fusion point can vary in different people, as in different lighting conditions. The flicker-fusion point can only be applied to digital images of absolute values, such as black and white. Where as a more analogous representation can run at lower frame rates, and still be perceived by a viewer. For example, motion blurring in digital games allows the frame rate to be lowered, while the human perception of motion remains unaffected. This would be the equivalent of introducing shades of gray into the black–white flicker.
Although human vision has no “frame rate”, it may be possible to investigate the consequences of changes in frame rate for human observers. The most famous example may be the wagon-wheel effect, a form of aliasing in the time domain; in which a spinning wheel suddenly appears to change direction when its speed approaches the frame rate of the image capture/reproduction system.
Different capture/playback systems may operate at the same frame rate, and still give a different level of "realism" or artifacts attributed to frame rate. One reason for this may be the temporal characteristics of the camera and display device.
Judder is a real problem in this day where 46 and 52-inch (1,300 mm) television sets have become the norm. The amount an object moves between frames physically on screen is now of such a magnitude that objects and backgrounds can no longer be classed as "clear". Letters cannot be read and looking at vertical objects like trees and lamp posts while the camera is panning sideways have even been known to cause headaches. The actual amount of motion blur needed to make 24 frames per second smooth eliminates every remnant of detail from the frames. Where adding the right amount of motion blur eliminates the uncomfortable side effects, it is more than often simply not done. It requires extra processing to turn the extra frames of a 120 FPS source (which is the current recording "standard") into adequate motion blur for a 24 FPS target. It would also potentially remove the detail and clarity of background advertising. Today, devices are up to the task of displaying 60 frames per second, using them all on the source media is very much possible. For example, the amount of data that can be stored on Blu-ray and the processing power to decode it is more than adequate. Though the extra frames when not filtered correctly, can produce a somewhat video-esque quality to the whole, the improvement to motion heavy sequences is undeniable. Televisions these days often have an option to do some kind of frame interpolation (what would be a frame between 2 real frames gets calculated to some degree), where for frames that are almost identical this can give some manner of improvement in judder, it comes nowhere close to a source having a higher number of frames, it is merely a trick to compensate for sources not having a high enough FPS rate. This interpolation creates artifacts on screen that are clearly noticeable also.