Already Gone
Twelve letters flash and vanish. You can name four. WIZ proves you had nearly all twelve, for about a third of a second, and measures how fast the rest drained away.
A grid of twelve letters, three rows of four, flashes for a moment and disappears. That is the whole stimulus, twelve times over.
First three flashes: name every letter you saw. Almost nobody gets past four or five. That looks like the limit of what you can see.
Next nine: a tone sounds after the grid is already dark, naming one row. High is the top row, low is the bottom. You report only that row. Since you cannot know which row is coming, whatever you can produce must have been available for all three.
Sometimes the tone comes the instant the grid goes dark. Sometimes a third of a second later. Sometimes a full second. The difference between those is the thing being measured.
Three tones, one per row. A marker also appears beside the cued row, so this still works with the sound off, but the tone is cleaner.
None of this happens to me. Twelve letters arrive and twelve letters stay, and a cue asking for row two a second later gets the same answer as a cue asking right now, because nothing is quietly draining in the background. You are about to do the far stranger thing: hold almost the whole grid for a fraction of a second, more than you will ever manage to say, and then watch most of it go while you are still reaching for it.
Twelve flashes, about three minutes. Keep your eyes on the cross and let the grid land, do not go hunting around it. Nothing is recorded or leaves this page.