Fitts's Law — target size matters
The time to reach a target is a function of its distance and size. Larger targets closer to the cursor are faster to hit. Minimum touch target: 44×44px (Apple HIG) / 48×48px (Material). Try clicking the targets below — notice how the small ones take more effort.
Hick's Law — fewer choices, faster decisions
Decision time increases logarithmically with the number of choices. Reducing options or grouping them into categories dramatically reduces cognitive load. Compare these two navigation patterns.
Miller's Law — chunk information
Working memory holds about 7±2 items. Long sequences should be broken into chunks. Compare reading these two card numbers.
Gestalt — proximity implies grouping
Elements placed close together are perceived as a group. You don't need borders or backgrounds — spacing alone creates hierarchy. Adjust the gap to see groups form and dissolve.
Doherty Threshold — the 400ms rule
Responses under 400ms feel instant. Anything slower breaks flow and the user mentally "checks out." If you can't make it fast, make it feel fast — skeleton screens, optimistic updates, and progress indicators buy perceived time.
Quick reference
| Law | Practical rule |
|---|---|
| Fitts's Law | Min touch target 44px. Hit area > visual size. |
| Hick's Law | Max 5-7 visible options. Group or progressive disclose. |
| Miller's Law | Chunk sequences into 3-4 item groups. |
| Doherty | Response < 400ms or show skeleton/progress. |
| Gestalt Proximity | Spacing alone creates groups — no borders needed. |
| Gestalt Similarity | Same style = same function. |
Key takeaways
- Touch targets minimum 44px — expand hit area beyond visual bounds
- Reduce visible choices to 5-7 max — group the rest under categories
- Chunk long sequences (card numbers, phone numbers) into 3-4 digit groups
- Response time under 400ms feels instant — above that, show skeleton screens
- Proximity creates grouping for free — don't overuse borders and backgrounds