On a list of black words, the single red one is the one you'll recall hours later.

The von Restorff effect, also called the isolation effect, says the item that stands out from its neighbors is remembered best. When most things look or sound alike, your attention snaps to the odd one out, and it gets encoded more distinctly, so it survives while the lookalikes blur together. The standout's advantage comes from contrast, not from being special on its own.

If you want something remembered - a point in a slide, a price on a menu, a name in a list - make it the one thing that breaks the pattern around it.

Learn the idea and practice English at the same time.