Behavior Fit Assessment

The Behavior Fit Assessment is a rapid evaluation tool for behavior selection. Before committing to a target behavior, validate three dimensions of fit for your population. If any dimension scores poorly, you’re forcing, not matching.

Positioning: This scoring is a decision tool (structured judgment), not an objective measurement instrument. Use it to make go/no‑go decisions and to surface what must be true for a behavior to be viable.

Intellectual Lineage

The Behavior Fit Assessment extends BJ Fogg’s foundational Fogg Behavior Model (B=MAP), first published in 2009

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. Fogg established that behavior occurs when Motivation, Ability, and Prompt converge at the same moment. The three-dimension structure of BFA builds directly on this insight:

Jason Hreha developed the Behavior Fit Assessment while working at Stanford’s Behavior Design Lab under BJ Fogg. The framework adapts Fogg’s behavior model for strategic product and program contexts, making it actionable for behavior selection decisions.

Note on parallel developments: The COM-B model (Michie et al., 2011) emerged two years after Fogg’s work with a similar structure (Capability, Opportunity, Motivation). Both frameworks recognize that behavior requires multiple factors to align. Behavioral Strategy prioritizes the Fogg lineage given its direct influence on this work.

The Three Dimensions

Identity Fit

Question: Does this behavior align with who they see themselves as?

Identity Fit measures whether the target behavior matches relatively stable individual differences — especially personality traits — plus self‑concept and status concerns. Identity/self‑concept measures add predictive power beyond attitudes and norms in classic intention models, and domain identities show meaningful associations with real behavior.

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See: Identity Fit, Personality, and Durable Behavior.

What it captures:

• How users see themselves (personality, values, self‑image)
• What they believe about the behavior (perception of value/feasibility)
• How the behavior affects their social standing (status implications)

Scoring guidance:

• 8–10: Behavior reinforces who they already are
• 6–7: Behavior is compatible with identity; no conflict
• 4–5: Behavior creates mild identity tension
• 1–3: Behavior conflicts with self‑concept; requires identity change

Example: Photo sharing on Instagram scores high on Identity Fit for users who see themselves as creative, social, and visually expressive. Location check‑ins scored low because most users don’t identify as “people who broadcast their whereabouts.”

Capability Fit

Question: Can they actually perform this behavior?

Capability Fit measures whether your population has the skills, resources, and practical ability to perform the behavior. This includes both inherent abilities and real‑world constraints (time, tools, cognitive load) that limit what’s possible.

What it captures:

• Skills and knowledge required
• Physical ability to perform the action
• Access to necessary tools or resources
• Environmental constraints (time, space, equipment)

Scoring guidance:

• 8–10: Behavior uses existing skills; trivially easy
• 6–7: Behavior requires minor learning or adjustment
• 4–5: Behavior requires meaningful skill development
• 1–3: Behavior requires capabilities most users lack

Example: Duolingo’s 5‑minute lessons score high on Capability Fit because most people can spare 5 minutes and tap on a phone screen. Traditional language classes requiring long sessions score lower because the time commitment exceeds many people’s available capacity.

Context Fit

Question: Does their environment support this behavior?

Context Fit measures whether the user’s physical and social environment enables or inhibits the behavior. This includes current emotional state, existing motivations, social norms, and environmental affordances/cues.

What it captures:

• Emotional compatibility (does their current state support the behavior?)
• Motivational alignment (does the behavior connect to existing goals?)
• Social environment (do norms and peers support this behavior?)
• Physical environment (does the setting enable the behavior?)

Scoring guidance:

• 8–10: Environment actively supports and reinforces behavior
• 6–7: Environment is neutral; no barriers
• 4–5: Environment creates friction; requires effort to overcome
• 1–3: Environment actively works against behavior

Example: Team messaging on Slack scores high on Context Fit because workplace environments require constant communication and the behavior integrates into existing workflows. Quibi’s 10‑minute mobile viewing scored low because phone contexts are interrupt‑driven; the environment works against focused viewing.

How to Use the Behavior Fit Assessment

Step 1: Define Your Population and Candidate Behaviors

Before scoring, clearly specify:

• Who is the target population? (Be specific: demographics, psychographics, and context)
• What behaviors are you evaluating? (List 3–5 candidate behaviors)

Step 2: Score Each Behavior

For each candidate behavior, score the target population on all three dimensions:

Step 3: Apply the Threshold Rule

Baseline minimum threshold: 6/10 on all three dimensions.

This threshold is a practitioner heuristic, a useful starting point derived from applied experience, not an empirically validated cutoff. Calibrate thresholds based on your domain, stakes, and population. In high-stakes contexts (e.g., healthcare), you may require higher thresholds; in exploratory contexts, you may tolerate more risk.

• If any dimension scores below your threshold, you’re forcing, not matching
• The limiting dimension (lowest score) determines behavior viability
• A behavior scoring 9/9/4 will fail; the 4 is the bottleneck

Step 4: Make the Selection Decision

If multiple behaviors pass threshold: Select the behavior with the highest minimum score (the one with the smallest gap between its strongest and weakest dimension).

If no behaviors pass threshold: Either:

1. Generate additional candidate behaviors, or
2. Design interventions to raise the limiting dimension, or
3. Reconsider whether this outcome is achievable for this population

Relationship to the Behavioral State Model

The Behavior Fit Assessment is the strategic, simplified view of the full Behavioral State Model.

Important note: Physical Environment is a single BSM component. In the Behavior Fit Assessment, it can show up as both a capability constraint (tools/time/resources) and as a context enabler (affordances/cues).

When to use the Behavior Fit Assessment:

• Strategic planning and behavior selection
• Rapid screening of candidate behaviors
• Initial prioritization before deep research

When to use the full Behavioral State Model:

• Diagnostic work when a behavior isn’t performing
• Intervention design targeting specific barriers
• Granular analysis of complex behavioral challenges

Examples (Illustrative)

Instagram vs. Burbn

Analysis: Check‑ins failed on Identity Fit (most users didn’t see themselves as “check‑in people”) and Context Fit (required remembering to act in moments with unclear payoff). Photo sharing matched all three dimensions. Users identified with it, could do it, and the context supported it.

Quibi’s Failure

Analysis: The behavior required a context that rarely exists (focused, uninterrupted mobile viewing), and it didn’t match the identity/context expectations of “premium” viewing. No amount of production value could overcome a behavior‑context mismatch.

Duolingo’s Success

Analysis: “Learner” is a broadly adoptable identity, the behavior is easy (capability), and micro‑lessons fit into real‑world contexts.

Common Mistakes

Scoring for Ideal Users, Not the Target Population

Mistake: Evaluating fit based on your most engaged users rather than your median target user.

Example: Power users love your complex dashboard. Scoring based on them suggests everyone will. But most users aren’t power users, so they score lower on Capability Fit.

Fix: Score for the median user in your target population. Segment if necessary and score separately.

Ignoring Identity Fit

Mistake: Focusing only on Capability and Context (“make it easy”) while ignoring whether users want to be the kind of person who does this behavior.

Example: Reducing friction to zero for a behavior users don’t value. They still won’t do it; they just have fewer excuses.

Fix: Check Identity Fit first. If users don’t see this behavior as compatible with who they are, no amount of ease will help.

Optimizing One Dimension at Another’s Expense

Mistake: Improving one fit dimension while damaging another.

Example: Adding gamification to boost Context Fit (making it fun) but triggering negative Identity Fit (users feel manipulated or childish).

Fix: Evaluate interventions across all three dimensions. A gain that creates a loss elsewhere often nets negative.

Key Takeaways

1. Three dimensions, one threshold. Identity Fit, Capability Fit, and Context Fit all must score ≥ 6 — as a practitioner heuristic (useful starting point, not an empirically validated cutoff).
2. The minimum score is the bottleneck. A behavior scoring 9/9/3 will fail. The 3 determines viability.
3. Identity Fit is a high-leverage constraint for durable behaviors. Personality is relatively stable, and identity/self‑concept measures predict intentions and correlate with real behavior.

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1. Context Fit includes motivation. It’s not just the physical environment; it’s whether emotions, goals, and norms support the behavior.
2. Behavior Fit Assessment is for selection; BSM is for diagnosis. Screen with BFA; troubleshoot with the full BSM.
3. Score for your actual population. Not ideal users, but your real median segment.

See also:

• Behavior Matching: The full process for selecting and validating behaviors
• The Behavioral State Model: The complete 8‑component diagnostic framework
• Four‑Fit Hierarchy: Where behavior selection fits into the validation sequence