Hook Model Framework

Framework for building habit-forming products. Based on a fundamental truth: habits are not created—they are built through successive cycles through the Hook.

Core Principle

The Hook Model = a four-phase process that connects the user's problem to your solution frequently enough to form a habit.

Trigger → Action → Variable Reward → Investment
    ↑                                      │
    └──────────────────────────────────────┘

Habit Zone: Products enter the "habit zone" when used frequently enough and with enough perceived value. The goal is to move users from deliberate usage to automatic, habitual behavior.

Scoring

Goal: 10/10. When reviewing or creating product engagement mechanics, rate them 0-10 based on adherence to the principles below. A 10/10 means full alignment with all guidelines; lower scores indicate gaps to address. Always provide the current score and specific improvements needed to reach 10/10.

The Four Phases

1. Trigger

Core concept: The actuator of behavior. What prompts the user to take action? Triggers come in two forms: external (environment-driven) and internal (emotion-driven). The ultimate goal is to move users from external triggers to internal triggers.

Why it works: Every habit starts with a cue. Without a trigger, there is no behavior. External triggers get users started, but internal triggers — emotions like boredom, loneliness, uncertainty, or fear of missing out — are what drive unprompted, habitual usage. When your product becomes the automatic response to an internal trigger, you have a habit.

Key insights:

• External triggers (push notifications, emails, buttons, ads, word of mouth) initiate behavior early on
• Internal triggers (emotions, routines, situations) are the ultimate goal — users prompt themselves
• The goal is to move users from external triggers to internal triggers over time
• Map your product to the specific negative emotion it resolves (boredom, loneliness, confusion, FOMO)
• Effective external triggers must be well-timed, actionable, and lead to the simplest possible next action

Product applications:

Copy patterns:

• "You might be wondering about..." (hooks into uncertainty)
• "Don't miss what happened while you were away" (FOMO trigger)
• "Your friend just..." (social/external trigger bridging to internal)
• "Pick up where you left off" (routine trigger)
• Notification copy should name the emotion: "Curious what's new?"

Ethical boundary: Never exploit vulnerable emotional states (depression, addiction, grief) as triggers. Triggers should connect users to genuine value, not manufacture anxiety to drive opens.

See: references/triggers.md for detailed trigger design, emotion mapping, and external-to-internal transition strategies.

2. Action

Core concept: The simplest behavior done in anticipation of a reward. Guided by the Fogg Behavior Model: B = MAT (Behavior = Motivation + Ability + Trigger). All three must converge at the same moment for action to occur.

Why it works: Increasing motivation is hard and unreliable. Reducing friction (increasing ability) is easier and often more effective. The key insight is that making the action simpler is almost always a better strategy than trying to increase motivation. Every extra step, field, or decision is a point where users drop off.

Key insights:

• Fogg Behavior Model: Behavior = Motivation x Ability x Trigger — all three must be present simultaneously
• Six elements of simplicity (ability): time, money, physical effort, brain cycles, social deviance, non-routine
• Increasing ability (reducing friction) is almost always more effective than increasing motivation
• The action should be the simplest behavior in anticipation of the reward — not the full task
• Hick's Law: more choices = slower decisions; reduce options to increase action rate

Product applications:

Copy patterns:

• "Just one tap to..." (emphasizes simplicity)
• "Takes less than 60 seconds" (time simplicity)
• "No credit card required" (money/risk simplicity)
• "We've set up defaults for you" (brain cycle simplicity)
• Buttons should be verbs: "Post", "Save", "Share" — not "Submit" or "Continue"

Ethical boundary: Reducing friction should make genuinely valuable actions easier — not trick users into actions they'd regret. Dark patterns that hide costs or consequences behind simple actions are unethical.

See: references/triggers.md for how triggers connect to the action phase, and references/product-applications.md for action design across product types.

3. Variable Reward

Core concept: The phase that keeps users coming back. The anticipation of reward — not the reward itself — creates dopamine. Critically, rewards must be variable (unpredictable) to maintain engagement. Predictable rewards lose their power over time.

Why it works: The brain's dopamine system responds most strongly to the anticipation of uncertain rewards, not to the rewards themselves. This is the slot machine effect: variable reinforcement schedules are far more engaging than fixed ones. Three types of variable rewards — tribe (social), hunt (resources), and self (mastery) — tap into fundamental human drives.

Key insights:

• Dopamine spikes during anticipation of uncertain reward, not upon receiving it
• Three types: Tribe (social validation), Hunt (search for resources/information), Self (personal mastery)
• Predictable rewards lose power; variability is what sustains engagement
• The "slot machine effect": uncertainty is what makes rewards compelling
• Autonomy is critical — users must feel in control; forced engagement backfires
• Finite variability (limited content) eventually becomes predictable; aim for infinite variability

Product applications: