Conversion & Growth Design

Apply behavioral psychology to design for action. Conversion is not manipulation — it's removing friction between user intent and the outcome they want.

Core Frameworks

Fogg Behavior Model

Behavior = Motivation × Ability × Prompt

All three must converge:

• Motivation — does the user want this? (emotion, anticipation, belonging)
• Ability — is it easy to do? (time, money, effort, skill)
• Prompt — is there a clear call to action? (trigger, nudge, reminder)

Design implication: If motivation is low, increase ability (make it effortless). If ability is low, increase motivation (show value). Always provide a clear prompt.

Hick's Law

More choices = longer decision time = more abandonment.

Apply: One primary action per screen. Highlight the recommended option. Collapse advanced options.

Cognitive Load Theory

Working memory is limited. Reduce mental effort.

Landing Page Design

The 5-Second Rule

A visitor decides whether to stay or leave in 5 seconds. Above the fold must communicate:

1. What this is
2. Why it matters to them
3. What to do next

Above-the-Fold Structure

┌─────────────────────────────────────┐
│  Logo          Nav          [CTA]   │  ← Navigation minimal
│                                     │
│  Headline: The value proposition    │  ← One clear benefit
│  Subhead: How it works (brief)      │  ← Clarify, not sell
│                                     │
│  [Primary CTA]  [Secondary CTA]     │  ← One primary action
│                                     │
│  [Visual: product/demo/social proof]│  ← Show, don't tell
└─────────────────────────────────────┘

Headline Formula

[Outcome user wants] + [How you deliver it] + [Timeframe if impressive]

Examples:

• "Ship your SaaS in weeks, not months"
• "Automatic backups that never slow you down"
• "The project management tool that actually gets used"

CTA Design

• Use first-person — "Start my free trial" outperforms "Start your free trial"
• Lead with a verb — "Get", "Start", "Create", "Download"
• Include the benefit — "Get the guide" not "Submit"
• One primary CTA per section — multiple CTAs compete and confuse

Persuasion Elements

Friction Reduction

Form Optimization

Checkout Optimization

• Guest checkout option (don't force account creation)
• Summary visible throughout (what, how much, when)
• Security signals near payment (SSL badge, encryption note)
• Multiple payment options
• Clear error messages with inline correction

A/B Testing for Conversion

Hypothesis Structure

"If we change [element] for [audience], we expect [result] because [behavioral reason]."

What to Test (Priority Order)

1. Headline and value proposition
2. CTA text and placement
3. Social proof placement and format
4. Form length and fields
5. Page length (short vs. long)
6. Visual hierarchy
7. Color (last — usually smallest impact)

Statistical Rigor

• Run for complete business cycles (full weeks)
• Reach 95% statistical significance
• Check guardrail metrics (don't improve conversion at expense of retention)
• Segment results (what works for mobile may not for desktop)

Dark Side Warning

Many growth tactics are dark patterns in disguise. Before implementing any persuasion technique, run it through the ethical filter:

• Is this genuinely helping the user?
• Would I be comfortable explaining this to a frustrated user?
• Am I creating real value or manufactured urgency?
• Can users easily undo this action?

If the honest answer to any of these is no, don't do it.

Reference Map

• references/fogg-hicks-checklist.md — Fogg B=MAP, Hick’s Law, 5-second fold checklist
• references/ab-test-priority.md — hypothesis template, test priority order, rigor gate

Related Skills

• For onboarding and activation → use onboarding-ux
• For landing page UX writing → use ux-writing-content-design
• For ethical boundaries → use ethical-design-patterns
• For A/B testing methods → use user-research-methods