Hallucination
Synonyms: model confabulation, fabricated content, AI bluffing, plausible nonsense
Definition
Use cases
- Chatbot misinformation: An AI-powered customer support bot hallucinates a return policy that doesn't exist, leading to user frustration and support tickets when human agents cannot honor the fake policy.
- Fabricated research: A product manager uses an AI summarization tool on user interview transcripts, and the tool hallucinates a key pain point that was never mentioned, misguiding the product roadmap.
How it's used in practice
- Design for verification: Implement source-citation UI elements. If an AI generates a summary, show exactly which part of the source document the information came from.
- Establish confidence levels: When displaying AI outputs, use visual indicators (like probability scores or color coding) to signal how confident the model is in its response.
- Implement human-in-the-loop workflows: For critical tasks (like generating medical advice or legal content), require AI-generated drafts to be reviewed and approved by a human expert before final delivery.
Challenges & limitations
- Identifying hallucinations: It is often difficult for users (and sometimes developers) to distinguish between a correct AI response and a plausible-sounding hallucination without manual fact-checking.
- Model unpredictability: Even with strict prompting, models can still hallucinate, making it difficult to create a consistently reliable user experience.
Free resources
- Vectara Hallucination Leaderboard — live scoreboard ranking models by hallucination rate.
- NN/g — AI Hallucinations: What Designers Need to Know — practitioner guide on why hallucinations are a permanent UX problem and how to design interfaces that flag them before users get burned.

