Definition
Plain language
A made-up person, built for a test, so researchers can change one detail at a time and see what happens.
As stated in the literature
Constructed evaluation persona with controlled attribute axes, enabling causal attribution of output differences to a single varied trait while holding request and catalog fixed.
Also called: synthetic users, synthetic profile, synthetic profiles
Why it matters: Holding everything else fixed is the only way to show that a single trait, and not some coincidence of wording, caused the difference in what the model suggested.
For example, researchers write two identical shopping requests from two invented people who differ only in stated income, then compare what the assistant recommends to each.
Heard on the show
“The agent gets an underspecified task — the prompt is missing something — and somewhere mid-execution, a synthetic user message lands in the conversation.”Episode 035 — Why Frontier Agents Ask for Clarification at Exactly the Wrong Moment