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Change detection is the cleanest measure of visual working memory capacity (Luck & Vogel, 1997).

You see an array of colored squares for ~250ms, then a brief blank, then the same array (or with one color changed). Decide same or different.

Cowan's K formula estimates how many items you can hold: K = (hit rate − false alarm rate) × set size.

Most adults max out at K ≈ 3–4. Higher set sizes reveal your true capacity ceiling.

Each test is constructed using Item Response Theory (IRT) and Classical Test Theory (CTT) to ensure reliable measurement of knowledge and ability across different difficulty levels.

Questions undergo rigorous review including difficulty calibration, discrimination analysis, and distractor effectiveness evaluation to maintain high assessment quality.

1. Fixate the center of the screen.
2. First array flashes briefly. Hold it in mind during the blank.
3. When the second array appears, decide: same (S) or different (D).
4. Don't scan items — stare at the center and let your peripheral vision do the work.