ux-expertise

UX Expertise

Foundational UX knowledge covering research methods, information architecture, interaction design patterns, accessibility standards, usability testing, content design, and service design. This skill provides the knowledge layer that all seven specialist agents draw from.

Core Frameworks

Nielsen's 10 Usability Heuristics

The primary evaluation framework for heuristic reviews:

1. Visibility of system status
2. Match between system and real world
3. User control and freedom
4. Consistency and standards
5. Error prevention
6. Recognition rather than recall
7. Flexibility and efficiency of use
8. Aesthetic and minimalist design
9. Help users recognize, diagnose, and recover from errors
10. Help and documentation

Load references/nielsen-heuristics.md for per-heuristic checklists and examples.

Laws of UX

Psychological principles for design decisions. Key laws:

• Fitts's Law: Target acquisition time = f(distance, size)
• Hick's Law: Decision time increases logarithmically with choices
• Miller's Law: Working memory holds 7 plus/minus 2 items
• Jakob's Law: Users expect your site to work like others they know
• Doherty Threshold: Productivity soars when response < 400ms
• Peak-End Rule: Experiences judged by peak intensity and ending

Load references/laws-of-ux.md for all 17 laws with origins and applications.

WCAG 2.2 Organized for Designers

Accessibility requirements organized by design responsibility:

Category	Key criteria
Visual design	Contrast 4.5:1 text, 3:1 UI; no color-only info; target 24x24px min
Interaction	Keyboard access all; no traps; focus visible; consistent nav
Content	Descriptive titles; heading hierarchy; labeled inputs; clear errors
Structure	Landmarks; reading order = DOM order; works portrait and landscape

Load references/wcag-22-design-guide.md for the complete organized checklist.

Research Method Selection

Choose methods by project phase:

Phase	Methods	Effort
Discovery	Contextual inquiry, stakeholder interviews, diary studies, competitive analysis	Medium-High
Definition	Personas, journey mapping, JTBD, service blueprints, task analysis	Medium
Design	Usability testing, A/B testing, tree testing, heuristic evaluation, cognitive walkthrough	Low-Medium
Measurement	Analytics review, SUS, HEART framework, task-level metrics	Low

Load references/research-methods.md for the complete framework with method details.

Information Architecture

The four systems of IA (Rosenfeld and Morville):

1. Organization: How information is categorized
2. Labeling: How information is represented
3. Navigation: How users browse (global, local, contextual)
4. Search: How users find

Navigation models: Hub and Spoke, Nested Doll, Tabbed View, Bento Box, Filtered View.

Load references/information-architecture.md for frameworks, card sorting, tree testing.

Interaction Patterns

Key pattern categories: Form Design, Navigation, Data Display, Feedback and Messaging, Onboarding, Complex Interactions (drag/drop, inline edit, bulk actions).

Load references/interaction-patterns.md for the complete pattern catalog.

ARIA Authoring Practices

Keyboard interaction models for every common widget: Accordion, Combobox, Dialog, Listbox, Menu, Tabs, Tree View, and more.

Load references/aria-patterns.md for the complete pattern set with keyboard models.

UX Metrics

Framework	Dimensions
Task-level	Completion rate, time on task, error rate, lostness, efficiency
SUS	10-item questionnaire, score 0-100, benchmark ~68
HEART	Happiness, Engagement, Adoption, Retention, Task success
AARRR	Acquisition, Activation, Retention, Revenue, Referral

Load references/ux-metrics.md for measurement frameworks and calculation methods.

Verifying Patterns Against Source

Always verify accessibility patterns against real implementations:

# Radix: focus management and ARIA
grep -r "aria-\|role=\|tabIndex\|onKeyDown" refs/radix-primitives/packages/react/dialog/src/
# axe-core: WCAG rules as code
grep -r "description\|help\|tags" refs/axe-core/lib/rules/ --include="*.json"
# ARIA practices: keyboard models
grep -r "keyboard\|key.*down\|arrow" refs/aria-practices/content/patterns/
# GOV.UK: research-backed patterns
grep -r "research\|evidence\|finding" refs/govuk-design-system/src/patterns/

Templates

Reusable deliverable scaffolds in templates/:

• templates/heuristic-evaluation/: Report with per-heuristic sections, severity scale
• templates/usability-test-script/: Moderator guide, tasks, metrics, SUS, debrief
• templates/research-plan/: Brief, questions, methods, participants, timeline
• templates/journey-map/: Phases, rows (actions/thoughts/feelings/touchpoints)
• templates/service-blueprint/: Layers (frontstage/backstage/support), lines of visibility
• templates/accessibility-audit/: WCAG checklist by level, issue template, scoring
• templates/ux-review/: Screen-by-screen format, priority matrix

Reference Files

• references/nielsen-heuristics.md: 10 heuristics with checklists and violation examples
• references/laws-of-ux.md: 17 UX laws with psychology origins and applications
• references/research-methods.md: Method selection by phase, study design guidance
• references/information-architecture.md: IA systems, navigation models, card sorting
• references/wcag-22-design-guide.md: WCAG 2.2 organized by designer responsibility
• references/aria-patterns.md: Keyboard interaction models per widget type
• references/interaction-patterns.md: Form, navigation, data display, feedback patterns
• references/ux-metrics.md: HEART, SUS, task metrics, AARRR frameworks
• references/service-design.md: Journey maps, blueprints, empathy maps, JTBD
• references/ux-writing-guide.md: Microcopy patterns, voice/tone, content hierarchy
• references/inclusive-design.md: Microsoft framework, disability spectrum, universal design