• What's the limitation of our eyes?

  • Can we differentiate 60fps from 120fps?

  • Are new 144hz monitors just a marketing trick?

Couldn't find any proper journals or studies about the matter.


closed as off-topic by ACuriousMind, user36790, John Rennie, RedGrittyBrick, Sebastian Riese Jan 5 '16 at 15:33

  • This question does not appear to be about physics within the scope defined in the help center.
If this question can be reworded to fit the rules in the help center, please edit the question.

  • $\begingroup$ Like the question, I am wondering if the eye is the limiting step tho, because consciousness has been measured at 40-90 frames per second per one source I read. Will follow what we hear from the community on this. $\endgroup$ – Ed Yablecki Jan 5 '16 at 13:23
  • $\begingroup$ Some interesting discussions here $\endgroup$ – Floris Jan 5 '16 at 13:33
  • $\begingroup$ "Are new 144hz monitors just a marketing trick?" Yes, just like the absurd numbers of pixels you see today, far smaller than the angular resolution of most people's poor eyesight. $\endgroup$ – user10851 Jan 5 '16 at 13:46
  • $\begingroup$ @ChrisWhite - you are right about numbers of pixels. Last year I was in the market for a new Mac, and went to see the 5k display. I was wowed. Then I noticed I was looking at the 2.5k display... they had been moved around in the shop, and even the Mac "genius" hadn't noticed. So I saved $700 on the display and upgraded my processor, memory, disk drive instead. :-) $\endgroup$ – Floris Jan 5 '16 at 14:25
  • 6
    $\begingroup$ I'm voting to close this question as off-topic because it is about human perception, not physics. $\endgroup$ – ACuriousMind Jan 5 '16 at 14:51

Different parts of the eye have different response speed. The corner of your eye doesn't see color, but is fast; the center sees color, and is slower. This means that when you look at a 60 Hz monitor straight-on, the image is perfectly steady; but when you look at it from the corner of your eye, it is flickering. As you go to even higher frequencies of refresh, even the rods don't respond fast enough.

This make sense from an evolutionary perspective. When the saber-toothed tiger jumps at you, you need to know about it - quickly. You don't need to know its color. So using the faster rods (sensitive, fast, no color sense) in the edge of the field of view is a good survival strategy. But since we can't move very far in 1/100th of a second, there is no need for sensors that respond at that speed.

The difference is real, and can be perceived. In the corner of your eye, for most people.

Incidentally, the rendering of fast motion is helped by the higher frame rate; if you show a bright object against a dark background moving left-to-right across the screen in 1/30th of a second, the brain will notice the difference between "two images comprise the full motion" and "four images comprise the full motion", even if you don't really perceive the individual frames. You will see a smoother action when more frames make up the motion: after all, in real life you really see "infinitely many frames" even though they blur together.


The conscious part of the human brain cannot process visual information that persists for less than about .04 seconds while the subconscious part is thought to be faster. What the brain is doing is pattern recognition in either case (which requires a considerable amount of mental processing). The issue is how long does this mental processing require and the implication is that the subconscious is faster than the conscious.

In the field of intelligence there is an hypothesis (based upon the above) called the 25th frame effect. If true it would enable someone to transmit subliminal information via a 25 fps video that incorporates an out of context frame at every 25th position. The subject would not be conscious of this attempted manipulation.

There was a rumor during the 1950s that movie theaters were subliminally encouraging customers to purchase food and drink items by inserting 25th frame images (of coke or popcorn, for example) just before the intermission. Congress passed a law against such subliminal manipulation as a result of this rumor.

During a presidential campaign in the US a number of years ago an add was aired in support of a republican candidate that included the word "Democrats" in the message. Some people noticed a flicker in the film while this word appeared and it was discovered that one frame of the add had dropped the first five letters of the word leaving "rats." The republicans vowed that this was not an illegal 25th frame attack against their opponent (attempting to form a subliminal association between Democrats and rats in the minds of voters) and no legal action was taken.


Not the answer you're looking for? Browse other questions tagged or ask your own question.