Planet Brightness Adaptation

[glend]

I ran across this statement on another forum.

"Some planetary observers, when observing in darkness, shine a white light on a piece of white card and stare at it for a short while to provoke the opposite of dark adaptation, and improve the contrast and colour of their intended targets."

It is the first time I have heard of brightness adaptation. Is this a valid technique for planetary observation? In particular does it enhance contrast definition, for spotting difficult features like Saturn Ring divisions? :question:
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[croweater]

Hi Glen, Maybe by forcing the pupil to close your eye focal ratio is slowed giving more resolution? :question: Just a wild assumption. Bit like looking through a small hole to help see small print.
Cheers, Richard. :)