ux-psychology-skilllisted

# UX Psychology Principles ## Overview 21 evidence-based psychology principles for building interfaces, plus Nielsen's 10 heuristics as an audit layer. Each principle in [reference.md](reference.md) has a rule, its psychological mechanism, concrete implementation moves, and guardrails separating the honest version from the dark-pattern version. **Priority order when principles conflict: usability > honesty > persuasion.** A persuasion pattern never justifies breaking a usability rule or a trust rule. Usability laws are load-bearing; persuasion is decoration on top. ## How to Use 1. **Before designing:** scan the Quick Reference below, then read the matching numbered sections in [reference.md](reference.md) for mechanism + implementation + guardrails of every principle you apply. 2. **While building:** apply interaction/perception laws (7–21) first; layer persuasion (1–6, trust) on top. 3. **Before declaring any screen done:** run the Review Checklist at the bottom of this file. It is the gate. ## Quick Reference **Persuasion & motivation (reference Part I)** | # | Principle | Rule | |---|-----------|------| | 1 | Smart Defaults | Pre-select the sensible choice for every field; never default anything costing money, data, or consent | | 2 | Goal Gradient | Never start progress at 0% — count what the user already did; ≤7 visible steps; at the end, flip to "1 step left" | | 3 | Reciprocity | Deliver standalone value before any signup gate; **never blur/lock results the us