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Author Topic: Do our eyes refresh?  (Read 3526 times)

Offline i_have_no_idea

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Do our eyes refresh?
« on: 14/02/2006 23:48:12 »
Do our eyes see at a certain frequency or refresh what we see hundreds of times a second like some cameras (taking pictures every second) or do we just somehow constantly see things?


 

ROBERT

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Re: Do our eyes refresh?
« Reply #1 on: 15/02/2006 17:56:04 »
"" A critical part of understanding these visual perception phenomena is that the eye is not a video camera: there is no "frame rate" or "scan rate" in the eye: instead, the eye/brain system has a combination of motion detectors, detail detectors and pattern detectors, the outputs of all of which are combined to create the visual experience.""
http://en.wikipedia.org/wiki/Persistence_of_vision
« Last Edit: 15/02/2006 17:58:07 by ROBERT »
 

Offline neilep

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Re: Do our eyes refresh?
« Reply #2 on: 15/02/2006 18:28:45 »
Thanks Robert...I was wondering about the answer myself because that was a good question Phil (I_have_no_idea)...

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Offline Dr B

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Re: Do our eyes refresh?
« Reply #3 on: 18/02/2006 18:00:26 »
When we stare at an object our eyes are actually making rapid small movements in order to refresh the receptor cells on the retina.  Is that true?

Dr B
Istanbul
 

another_someone

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Re: Do our eyes refresh?
« Reply #4 on: 18/02/2006 21:54:21 »
quote:
Originally posted by Dr B

When we stare at an object our eyes are actually making rapid small movements in order to refresh the receptor cells on the retina.  Is that true?




I don't have a definitive answer for this, but there are a few things that I am aware of that may be relevant.

Most importantly, we do not have an even acuity throughout our field of view.  Our vision is more acute near the centre of the field of view, and less so towards the periphery of our vision, excepting we have a blind spot exactly where the optic never comes into the eye.  Thus it would make sense that the eye would shift the centre of vision from place to place in order to pick up specific detain about different parts of the field of vision.

It may also be that the eyes will try ant fix on an object to judge its range more accurately, and in doing so the eyes will converge upon that object (since, with both eyes looking along exactly parallel tracks would mean that the point of convergence would be at infinity).



George
 

Offline daveshorts

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Re: Do our eyes refresh?
« Reply #5 on: 20/02/2006 09:05:57 »
Your eyes are more sensitive to high speed movements in your peripheral vision than in the centre, this is why monitors sometimes flicker at the edge of your vision, but if you look directly at the monitor it looks fine.
 

ROBERT

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Re: Do our eyes refresh?
« Reply #6 on: 20/02/2006 13:34:42 »
quote:
Originally posted by Dr B

When we stare at an object our eyes are actually making rapid small movements in order to refresh the receptor cells on the retina.  Is that true?

Dr B
Istanbul



I believe you are referring to "Saccidic Movements".
As Another Someone said, only the central part of the field of view is sharp: the sharp area is not large enough to image (say) an entire face at once, so these small Saccidic movements scan the sharp area over the face to bulid up a sharp image (in the brain).
« Last Edit: 20/02/2006 13:44:05 by ROBERT »
 

Offline i_have_no_idea

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Re: Do our eyes refresh?
« Reply #7 on: 21/02/2006 01:23:03 »
Do light bulbs flash at a cretin frequency?

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ROBERT

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Re: Do our eyes refresh?
« Reply #8 on: 22/02/2006 11:38:56 »
quote:
Originally posted by i_have_no_idea

Do light bulbs flash at a cretin frequency?



Incandescent lightbulbs (typical 60/100Watt types) flicker at mains frequency :
50Hz (50 times per second) in UK, 60Hz in USA.

Flickering / flashing lights can induce seizures in epileptics:-
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=11593256&query_hl=1&itool=pubmed_docsum

I'm not sure how flashing lights would affect "a cretin"   :)
http://www.thefreedictionary.com/cretin
http://www.answers.com/topic/cretinism

« Last Edit: 22/02/2006 11:40:37 by ROBERT »
 

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Re: Do our eyes refresh?
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