L005 · How AI thinks · 2 min · Interactive
Why AI makes things up
AI is built to produce a likely answer, not a true one, so sometimes it confidently invents facts.
01 · The idea
When a chatbot invents something, like a fake book title, a wrong date or a law that does not exist, it is called a hallucination.
It happens because the model is predicting text that looks right. If it does not know the answer, it rarely says so. It fills the gap with something that fits the pattern.
Hallucinations are most common with exact details: names, numbers, quotes, links, citations and recent events. They are less common with general explanations.
Newer models hallucinate less, and many can search the web and show sources. But no model is free of it yet. Try it below: three answers, one is invented. Can you spot it?
02 · Think of it like this
It is like a student in an exam who did not study one topic but writes a confident paragraph anyway, because a blank page feels worse than a guess.
03 · Try the toy
Spot the made-up fact
Each answer sounds sure of itself. One contains something invented. Tap the one you think is fake.
Who wrote the novel “One Hundred Years of Solitude”?
04 · Do it now
05 · Quick check
Words in this lesson
See also
L025Under the hood · 2 min
RAG: give AI your documents
RAG lets a chatbot look up the right pages in your own documents before it answers, so it can use facts it was never trained on.
L082Asking well · 2 min
Prompt in Vietnamese or English?
Write in the language you think in, and ask for the answer in the language you need.
L144Staying safe · 2 min
Using AI safely for health questions
AI can help you understand a diagnosis or prepare questions for your doctor, but it cannot examine you and may be confidently wrong.
L003How AI thinks · 1 min
What a chatbot really does
A chatbot writes its answer one small piece at a time, each time picking a likely next word.