Medical Does the human eye have a refresh rate ?

  1. Does the human eye have a "refresh rate"?

    This question probably seems ridiculous, but I have no background in physiology and I cannot find anything discussing it online or in my roommate's physiology textbook.

    I was wondering if anyone here knows whether the eye and brain processes information continuously, or if it takes rapid "snapshots."
  2. jcsd
  3. DaveC426913

    DaveC426913 16,537
    Gold Member

    Re: Does the human eye have a "refresh rate"?

    Sort of, yes. It's about 1/10 of a second. It's why we can see a flipbook of discrete doodles as if it is continuous motion. And why TV works (1/25th second), and why fluorescent lights seem to be continuous (1/60th second).

    Read up on persistence of vision. (A quick pre-emptive search shows that, while it seems there's a bit of debate about the actual mechanism for the effect, the 1/10 second rule still seems to apply.)
    Last edited: Aug 29, 2009
  4. russ_watters

    Staff: Mentor

    Re: Does the human eye have a "refresh rate"?

    I wouldn't call persistence of vision a "refresh rate". Our vision is more like a continuous signal that takes a finite time to respond to changes.
  5. Danger

    Danger 9,663
    Gold Member

    Re: Does the human eye have a "refresh rate"?

    I don't know enough about the physiology, but the reason that a standard TV refreshes at 30 frames per second is because that is about the slowest rate at which continuous motion is perceived.
    I do know, due to my weapons design hobby, that a light flashing at 16 pulses per second is interpreted by the visual cortex as being constantly 'on'. The rest of the brain, though, recognizes the individual flashes. It's weird, but it can sure come in handy if you want to mess with someone. :biggrin:
  6. Re: Does the human eye have a "refresh rate"?

    yes, there is something to it. it's why a spinning spoked wheel can appear to be rotating backwards, aliasing. and yes, it happens in real life, too, not just a film artifact.
  7. Re: Does the human eye have a "refresh rate"?

    That sounds way too slow to current monitor does not that low so I can't double check this but I'm pretty sure I can see flickering on 60 hz monitors
  8. Re: Does the human eye have a "refresh rate"?

    Right. There is some kind of complex multiplexing that occurs in the brain and/or that ganglia between the eyes & brain, which is unrelated to the persistence of vision--which is mostly just a lag in the chemical reactions in the retina. My theory is that its something like a vortex scan, where the vortex spins faster near the fovea. I get opthalmic migraines (migraines with the pre-aura but no pain afterwards, thank goodness), and the blind spot always has a definite periodic jagged shimmering around its edge.
  9. Re: Does the human eye have a "refresh rate"?

    Thank you all for responding. Best wishes =)
  10. Re: Does the human eye have a "refresh rate"?

    Wait, What??
    This is not true.
    In daylight you will not see spokes going backwards, you will only see a blur.
    When lit by artificial light the light will act as a stroboscope and this will trigger the effect.

    Wave your hand in sunlight and notice that the blur is not composed of separate overlaying 'snapshots' of your hand (well, in the corners where your hand effectively stops it might seem that way, in fact you just get a longer exposure time for the hand and a less transparent image is formed.).
    In case there was a 'refresh rate' in the eyes you would see separate transparant versions of your hand overlayed instead of the blur.

    Your eyes are not camera's!
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