1What your eye does with light
Your eye has a door — and a chemical that catches light
You only need two ideas. Watch each one:
A door that opens wide
The black dot in your eye is a hole — the pupil. In bright light it shrinks small. In the dark it opens wide to let more light in. It begins changing within seconds.
A light-catcher chemical
Inside the back of your eye, tiny catchers use a special chemical to grab light and shout "I saw something!" Bright light changes many of those molecules into a form that must be recycled before it can catch light again.
2Your turn — work the door
Dim the room and watch the pupil open
Slide the room from bright to dark and watch the black dot. The pupil is the fast part — it reacts within seconds. This practice view shows only pupil size. In the experiment, we will keep that size fixed and inspect the same dim room at two times.
3Now the real test
Same dim room, same pupil — two different waits
The model pupil is already wide open. Keep the room light and pupil size fixed. Compare the first look with a later look: will the same faint shapes become easier to see?
Guess before you find out
With the pupil already wide and the room unchanged, will waiting make the faint shapes clearer?