# Test: Usability Testing & Iteration

**Track:** Design Thinking & Process — Design & Human-Centered Design — proposed (25)
**Framework / surface:** design
**Level:** Intermediate
**Prerequisites:** Prototype: Fidelity & Making Tangible

**In one line:** Watch real people use it; learn; iterate — the loop that closes the process.

## Theory, aesthetics & inspiration

Usability testing closes the design loop: you watch real people attempt real tasks rather than asking whether they like an interface — behavior, not opinion, is the data. The think-aloud protocol, grounded in K. Anders Ericsson and Herbert Simon's "Protocol Analysis" (1984), has participants narrate their reasoning so confusion becomes audible. Jakob Nielsen's "Why You Only Need to Test with 5 Users" (2000) argues five testers surface about 85% of problems, so frequent small-n rounds beat one large study — now routinely run as remote, unmoderated sessions. Steve Krug's "Don't Make Me Think" (2000) reframes this as cheap, continuous practice: observe, fix, re-test.

## References

- [Usability testing — Wikipedia](https://en.wikipedia.org/wiki/Usability_testing)
- [Why You Only Need to Test with 5 Users — Nielsen Norman Group](https://www.nngroup.com/articles/why-you-only-need-to-test-with-5-users/)
- [Think-aloud protocol — Wikipedia](https://en.wikipedia.org/wiki/Think-aloud_protocol)