── ── Cognitive bias
Halo Effect
A single positive or negative impression biases judgments of all unrelated attributes. A "great" CEO is assumed to have great strategy, vision, and execution; a beloved brand's features are rated higher than equivalent features from less-loved brands. Documented by Thorndike (1920), formalized by Nisbett & Wilson (1977), applied to business analysis by Rosenzweig (2007) — who showed business books overclaim…
Run Halo Effect on a real problem
Bring something you're actually deciding — free, in the browser.
How it works
Composes with fundamental-attribution-error, narrative-fallacy, confirmation-bias, hindsight-bias, survivorship-bias.
When to use it
- user is conducting a performance review or hiring interview
- someone says 'she's great across the board' or 'everything they do is excellent'
- user is evaluating a vendor, CEO, or investment and all attributes look uniformly positive or negative
- user is reading business books or analyst reports and wants to assess whether the lessons generalize
- user suspects their overall impression of a person or brand is distorting specific judgments
When not to use it
When the decision is routine and reversible, applying a formal method costs more than it returns.
Worked example
The "AI" Halo — Builder.ai and the AI-Washing Wave (2023–2026)
Between 2023 and 2026, the two letters "AI" functioned as the strongest halo in business evaluation: a single glowing attribute ("they're an AI company") that silently inflated investors' ratings of every other attribute — revenue quality, technology depth, management integrity, even audit reliability. The cleanest documented case is Builder.ai, a Microsoft-backed "AI-powered app development" unicorn once valued around $1.5 billion, which filed for insolvency in May 2025 after its revenue and its "AI" both turned out to be substantially less than the halo suggested. Regulators…
Install this skill (free, MIT)
npx skills add deciqAI/knowledge-skillsUseful? Star the repo — stars help other builders find it.
Related mental models
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Hindsight bias — the "I knew it all along" effect — is the tendency, after learning an outcome, to misremember your prior judgment as having been…
John Kotter built this model from studying one hundred corporate transformations — most failed.
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