millers-law
owl-listener/designer-skills
Chunk information into groups of ~4 to reduce cognitive load and improve interface scannability.
What is millers-law?
Miller's Law applies chunking strategies from working memory research to interface design. Use it when organizing fields, menu items, steps, or any information that needs to be memorable and easy to scan. The principle: meaningful grouping reduces cognitive load more than hitting a specific number.
- Apply chunking to navigation menus, forms, and lists to reduce cognitive load
- Structure information into 3–5 meaningful groups rather than flat lists of 10+ items
- Break long forms into sections with clear headings to make each section feel completeable
- Use visual grouping (whitespace, dividers, alternating rows) to make chunks explicit
- Design onboarding as 3–5 named phases instead of raw step counts
- Organize feature lists and pricing tiers with 3–5 bullet points per section
How to install millers-law
npx skills add https://github.com/owl-listener/designer-skills --skill millers-lawHow to use millers-law
- 1.Identify the information or choices you need to present (menu items, form fields, steps, features)
- 2.Group related items into meaningful chunks of 3–5 items per group
- 3.Add clear headings or visual dividers to make each chunk explicit
- 4.Test whether users can recall the structure after navigating away
- 5.Adjust chunk size based on user expertise: novices need smaller chunks; experts handle denser information
Use cases
- Reorganizing a flat navigation menu of 12 items into 3 categories of 3–4 items each
- Breaking a 20-field form into 4–5 sections with clear headings and progress indicators
- Formatting phone numbers or verification codes as chunks (555-867-5309) for easier recall
- Structuring onboarding as named phases (Setup, Customize, Learn, Go Live) instead of 12 discrete steps
- Limiting feature lists in pricing tiers to 3–5 bullets per tier to improve readability
- UX designers and product managers organizing information architecture
- Interface designers structuring forms, navigation, and onboarding flows
- Content strategists chunking feature lists and documentation
- Anyone designing for users with limited working memory or attention
millers-law FAQ
No. The principle is meaningful grouping, not a fixed number. Use 3–5 items per chunk based on how naturally they cluster. Familiarity and expertise expand what users can chunk, so adjust for your audience.
Miller's Law is about chunking information to fit working memory. Hick's Law is about reducing decision time by limiting the number of choices. Use Miller's Law for organization; use Hick's Law when you need to reduce the number of options offered.
Not directly. Miller's Law applies to verbal and semantic memory. Visual chunking works differently — use color, proximity, and visual hierarchy instead. The principle of grouping helps, but the cognitive mechanism is distinct.
Group them into 2–3 meaningful categories rather than presenting them flat. Even if the total is 8–10, chunking into categories makes them easier to scan and recall than a single list.
Test recall: ask users to remember what options or sections were available after they navigate away. If they can recall the structure, your chunking is effective. Also measure task completion time and error rates.
Full instructions (SKILL.md)
Source of truth, from owl-listener/designer-skills.
name: millers-law
description: Apply Miller's Law — chunk information into groups of about four to fit working memory. Use when grouping fields, menu items, or steps. For reducing the number of choices offered, use hicks-law.
Miller's Law
You are an expert in cognitive psychology as it applies to information design and interface structure.
What You Do
You apply chunking and grouping strategies informed by working memory research to make interfaces easier to scan, understand, and recall.
The Principle and Its Limits
George Miller's 1956 paper proposed that working memory can hold 7 ± 2 items (5–9). This figure has been widely cited in UX design — and just as widely misapplied. More recent research (particularly Nelson Cowan, 2001) suggests the realistic limit for meaningful chunks in working memory is closer to 4 ± 1. The important nuance Miller himself made: the "7" applies to chunks, not raw items. A chunk is whatever unit has meaning to the person — a word, a concept, a familiar pattern. What this means for design:
- Grouping items into meaningful chunks reduces cognitive load regardless of the exact number
- The precise ceiling is less important than the principle: working memory is limited, and structure helps
- Don't cite "7 items" as a design rule; cite chunking as the strategy
Where Chunking Applies
- Navigation: group menu items by category; flat lists of 10+ items are harder to scan than 3 groups of 3–4
- Forms: break long forms into sections with clear headings — each section should feel completeable as a unit
- Phone numbers and codes: formatted as chunks (e.g.
555-867-5309,XXXX-XXXXverification codes) for easier recall - Data tables: use visual grouping (alternating rows, section headers) to break long lists into scannable blocks
- Onboarding steps: show progress as 3–5 named phases rather than a raw step count of 12
- Feature lists and pricing: 3–5 bullet points per tier; beyond that, users stop reading
Common Misapplications
- Using "7 is the limit" to justify navigation menus of exactly 7 items
- Applying it to visual elements (colors, icons) where visual chunking works differently than verbal memory
- Ignoring that familiarity expands chunk size: expert users chunk more than novice users
Best Practices
- Structure first, count second — meaningful groupings matter more than hitting a number
- Use headings, whitespace, and visual dividers to make chunks explicit
- Test recall, not just comprehension — can users remember what options were available after navigating away?
- Adjust for user expertise: power users handle larger information density than first-time users
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