HOW IT WORKS: The time required to select a target increases with distance and decreases with size. Interfaces become faster and more accurate when important controls are large, easy to reach, and placed in predictable locations.

IN UX/UI/AI DESIGN: UX, UI, and AIX designers place primary actions within comfortable reach, enlarge touch targets, and reduce pointer travel. AI interfaces adapt layouts to usage context and accessibility needs to improve speed and accuracy.

EXAMPLE: A mobile app places the main action button near the thumb zone and enlarges it for one‑hand use, while an AI assistant highlights the next likely action with a larger interactive area.