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Joined: Jul 2010
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Ok.... I need to know why the pupil changes from small to big?
When a show in cinema starts... Our pupil will change from small to big or big to small?
When we wear glasses, our pupil will change its size?
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Joined: Dec 2010
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Well, I am definitely no expert, but I will try. The pupil of the eye changes in response to the level of the light that hits them. If the light is bright the pupils will be small, if the light is dim they will be larger. This is of course an attempt to keep the amount of light reaching the retina at a reasonable level, just as the f-stop of a camera is adjusted so the correct amount of light reaches the film.
As far as in the cinema is concerned. If the light in the theater is dim before the show starts then the pupils will be large, and will contract when the screen lights up. Just how much will depend on the light level received from the screen.
I don't think that wearing glasses will cause the pupil to change size. The size of the pupil is based on the light level, and I don't think that glasses will make any significant difference. Of course if the glasses are very strong they might magnify the size of the eyes as seen by somebody else, but the whole eye would appear larger, not just the pupil.
Bill Gill
C is not the speed of light in a vacuum.
C is the universal speed limit.
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Well, I am definitely no expert, but I will try. The pupil of the eye changes in response to the level of the light that hits them. If the light is bright the pupils will be small, if the light is dim they will be larger. This is of course an attempt to keep the amount of light reaching the retina at a reasonable level, just as the f-stop of a camera is adjusted so the correct amount of light reaches the film...........>
Bill Gill
What a good explanation Bill Gill!
Cant do much better than that, the only other reasons for Pupil dilation is :-
taking drugs, or the eyedrops, an Optometrist might give you (sorry the Optician) to relax the eye and open the pupil before an eye test to look at the retina better? Belladonna (digitalis), a poison from Foxglove flowers, is often used as eydrops by middle eastern ladies to brighten and enlarge their eyes. Atrophine is also used by opticians to dilate pupils.
Strange you cannot feel your pupils getting larger or smaller. The only way I know is to look into a mirror and shine a torch around my eye.
Then one see's a beautiful smooth natural reflex, but no movement is felt.
.  . "You will never find a real Human being - Even in a mirror." ....Mike Kremer.
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I'd recommend searching the web for info about pupil dilation and emotional response. E.g.: http://wzus1.search-results.com/r?t=p&d=apn&s=zdo&c=a&l=dis&o=15914&sv=0a5c4240&ip=76ae7a9f&id=D13D21DF075221967DE85FB81F376E84&q=pupil+response+to+emotion&p=1&qs=121&ac=24&g=2b56DjUSqtv89j&en=gs&io=0&ep=&eo=&b=a001&bc=&br=&tp=d&ec=1&pt=Pupillometry&ex=&url=&u=http://webpub.allegheny.edu/employee/a/adale/p360/Pupillary%20Response%20Presentation%5B1%5D.ppt "Pupil dilation has been scientifically connected to emotional responses since Cluade Bernand and Charles Darwin in the 1850's" ( NOTE: The above is a small download in MS Powerpoint format) http://scan.oxfordjournals.org/content/1/1/3.full"Pupil size is well-known to be influenced by stimulus luminance, but it turns out also to be influenced by other factors, including salience and emotional meaning." http://psycnet.apa.org/index.cfm?fa=buy.optionToBuy&id=2009-12449-005"higher pupil dilation associated with easy-to-process stimuli"
"Time is what prevents everything from happening at once" - John Wheeler
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Joined: Dec 2010
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You are quite right rede. I knew all that and forgot a lot of it. I thought about including the information about the various substances that cause pupil dilation. I decided not to include it since it was sort of a special case.
But I completely forgot about the response to other stimuli, such as seeing something, or someone, who is attractive.
Bill Gill
C is not the speed of light in a vacuum.
C is the universal speed limit.
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