--- title: "Reference index" source: "/reference" description: "30 established principles in 5 categories, plus 2 original Layr rules." --- # Design principles and Layr rules. 30 established principles in 5 categories, plus 2 original Layr rules. Open a rule for examples, source links, and agent guidance. ## 01 — Perception & Visual Hierarchy Rules for making visual relationships, priority, state, and interaction meaning legible before the user has to read every detail. - [Aesthetic-Usability Effect](/__layr/pages/reference/aesthetic-usability-effect.md) — People often approach a polished interface with more patience and a stronger initial expectation that it will be easy to use. - [Law of Common Region](/__layr/pages/reference/law-of-common-region.md) — Elements enclosed by the same visible boundary are usually interpreted as belonging together. - [Law of Proximity](/__layr/pages/reference/law-of-proximity.md) — Items placed near one another are commonly read as a group, even when no border connects them. - [Law of Prägnanz](/__layr/pages/reference/law-of-pragnanz.md) — When a visual structure is ambiguous, people tend to resolve it into the simplest coherent interpretation available. - [Law of Similarity](/__layr/pages/reference/law-of-similarity.md) — Elements that look alike are likely to be interpreted as sharing a role, state, or category. - [Law of Uniform Connectedness](/__layr/pages/reference/law-of-uniform-connectedness.md) — Visible connections make elements feel more strongly related than elements that merely share space. - [Selective Attention](/__layr/pages/reference/selective-attention.md) — People allocate attention toward a limited subset of what is visible, usually guided by their current goal, expectations, and salient cues. - [Von Restorff Effect](/__layr/pages/reference/von-restorff-effect.md) — A distinctive item within a group is more likely to attract attention and be remembered than neighboring items that look alike. ## 02 — Memory & Cognition Rules for reducing unnecessary mental work, supporting recognition, preserving context, and helping users build reliable expectations about the system. - [Chunking](/__layr/pages/reference/chunking.md) — Information becomes easier to process when related pieces are organized into meaningful units that can be understood as one structure. - [Cognitive Bias](/__layr/pages/reference/cognitive-bias.md) — Judgment is shaped by predictable mental shortcuts, prior beliefs, framing, defaults, salience, and context. - [Cognitive Load](/__layr/pages/reference/cognitive-load.md) — Every task consumes limited mental resources; interface complexity adds cost when users must remember, infer, translate, compare, or recover information unnecessarily. - [Mental Model](/__layr/pages/reference/mental-model.md) — People operate a product through an internal explanation of what the system is, what its objects mean, and what actions will cause. - [Miller's Law](/__layr/pages/reference/millers-law.md) — Human short-term information processing is limited; the famous 'seven plus or minus two' finding should be treated as historical context, not as a universal UI item limit. - [Working Memory](/__layr/pages/reference/working-memory.md) — Working memory temporarily holds and manipulates information needed for the task currently in progress. - [Serial Position Effect](/__layr/pages/reference/serial-position-effect.md) — Items near the beginning and end of a sequence often receive stronger recall than items in the middle. ## 03 — Decision, Simplicity & Familiarity Rules for structuring choices, managing complexity, using familiar conventions, and helping users reach correct decisions without unnecessary interpretation. - [Choice Overload](/__layr/pages/reference/choice-overload.md) — A large or poorly structured set of alternatives can make selection slower, more stressful, or easier to abandon. - [Hick's Law](/__layr/pages/reference/hicks-law.md) — Decision time tends to increase as the number of plausible choices and the uncertainty between them increase. - [Jakob's Law](/__layr/pages/reference/jakobs-law.md) — Users bring expectations learned from other products and usually benefit when familiar conventions continue to behave in familiar ways. - [Occam's Razor](/__layr/pages/reference/occams-razor.md) — When several designs solve the same problem equally well, prefer the one that introduces fewer assumptions, mechanisms, and moving parts. - [Pareto Principle](/__layr/pages/reference/pareto-principle.md) — A minority of features, actions, or causes often account for a disproportionate share of use or outcomes; the exact ratio is context-dependent. - [Paradox of the Active User](/__layr/pages/reference/paradox-of-the-active-user.md) — People often prefer to begin doing the task immediately rather than first investing time in manuals or complete instruction. - [Tesler's Law](/__layr/pages/reference/teslers-law.md) — Some complexity belongs to the problem itself; design determines where that complexity is handled and who must carry it. ## 04 — Interaction, Performance & Error Tolerance Rules for responsive controls, reachable targets, resilient input, bounded tasks, and recovery patterns that keep the interface trustworthy under real-world conditions. - [Doherty Threshold](/__layr/pages/reference/doherty-threshold.md) — Interaction feels fluid when feedback arrives quickly enough that users can maintain a continuous task rhythm. - [Fitts's Law](/__layr/pages/reference/fitts-law.md) — Acquiring a target generally becomes easier as the target grows and as the required pointer travel decreases. - [Postel's Law](/__layr/pages/reference/postels-law.md) — Interfaces benefit when they accept reasonable variation in user input while producing clear, predictable output. - [Parkinson's Law](/__layr/pages/reference/parkinsons-law.md) — Work tends to expand to fill the time or space available; in product design, loose task boundaries can encourage unnecessary effort. ## 05 — Motivation, Progress & Experience Memory Rules for sustaining effort, making progress legible, supporting interrupted work, and designing the moments that shape how an experience is remembered. - [Flow](/__layr/pages/reference/flow.md) — Sustained engagement is more likely when the task, feedback, difficulty, and user capability remain in a productive balance. - [Goal-Gradient Effect](/__layr/pages/reference/goal-gradient-effect.md) — Motivation can strengthen as people perceive themselves getting closer to a meaningful goal. - [Peak-End Rule](/__layr/pages/reference/peak-end-rule.md) — People often remember an experience disproportionately through its most intense moments and how it concludes. - [Zeigarnik Effect](/__layr/pages/reference/zeigarnik-effect.md) — Incomplete activity can remain mentally salient, which makes visible unfinished work a powerful cue to resume a task. ## Layr Principles - [LAYR-001 — The Intentionality Law](/__layr/pages/reference/layr-001-intentionality.md) — Every visible decision should support meaning, action, identity, accessibility, or comprehension. Remove what does none of those. - [LAYR-002 — The Complete Flow Law](/__layr/pages/reference/layr-002-complete-flow.md) — A feature is complete when the user can enter, understand, act, wait, succeed, fail, recover, and continue through the surrounding task.