[Neuroscience] Re: Light and dark adaptation of the eye

Tim Allen via neur-sci%40net.bio.net (by tim.allen from gmx.com)
Sat Oct 14 17:22:17 EST 2006

r norman wrote:
> I am not sure just what you mean.  The receptors can only adapt to the
> light intensity to which they, themselves, are exposed.  There is no
> 'eye averaging' system that measures an 'overall' illumination and
> gets all the receptors to adapt to that level.

Well, thanks - what you explained was exactly what I meant!

> However it is true that generally all the receptors in the eye are subject to an overall
> exposure to  the same background light intensity with the image
> producing only a relatively minor change in intensity for specific
> receptors.

So, to take this a bit further, could it be said that this "locally
variable adaptation" increases the contrast range that the eye (the
photoreceptors) is (are) able to deal with?

Tim Allen

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