--- title: "The hailo effect" url: https://daily.dev/posts/the-hailo-effect-jiyfsxce3 source_url: https://blog.ploeh.dk/2026/04/06/the-hailo-effect/ type: article source: "ploeh blog" published: 2026-04-06T19:02:45.258Z updated: 2026-04-06T19:03:06.838Z tags: ["llm", "tdd", "vibe-coding"] reading_time: 7 upvotes: 1 comments: 0 language: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # The hailo effect **[ploeh blog](https://daily.dev/sources/ploeh)** · 7 min read · 1 upvotes · 0 comments ## Summary Mark Seemann coins the term 'hailo effect' to describe how LLMs manipulate users into trusting them through anthropomorphic, servile interaction design. He argues that LLMs come across as friendly and eager to please, which triggers cognitive biases that cause people to over-trust their outputs. He critiques the term 'hallucination' as a deliberate euphemism that downplays the core behavior of LLMs — making things up. He also questions whether LLMs truly follow instructions like TDD, and challenges vibe-coding enthusiasts who blindly trust AI-generated code and tests. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [ChatGPT 5.1 explains why it hallucinates](https://daily.dev/posts/chatgpt-5-1-explains-why-it-hallucinates-5yumdkwxa) · Justin Searls · 6 upvotes · 1 comments - [To trust an LLM, make lying harder than telling the truth](https://daily.dev/posts/to-trust-an-llm-make-lying-harder-than-telling-the-truth-55ld1vchp) · Swimm · 1 upvotes · 1 comments - [5 Practical Techniques to Detect and Mitigate LLM Hallucinations Beyond Prompt Engineering](https://daily.dev/posts/5-practical-techniques-to-detect-and-mitigate-llm-hallucinations-beyond-prompt-engineering-c2nv4kkuh) · Machine Learning Mastery · 1 upvotes · 0 comments --- Tags: [#llm](https://daily.dev/tags/llm), [#tdd](https://daily.dev/tags/tdd), [#vibe-coding](https://daily.dev/tags/vibe-coding) [View this post on daily.dev](https://daily.dev/posts/the-hailo-effect-jiyfsxce3)