An Extinction Illusion

There are 12 dots on this grid. When they are reduced in size, and outlined in black, they disappear.  only a few of them are visible at a time, in clusters which move erratically on the page. Where they are not seen, the grey alleys seem to be continuous, generating grey crossings that are not actually present. Some black sparkling can be seen at those crossings where no disk is seen.

How many dots can you see at a time?

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