Default Dominance: Most Users Never Change the Setting You Ship

Jakob Nielsen shows that most users keep whatever setting a product ships, and argues that AI agents hide their defaults in instruction files that need an owner.

Jakob Nielsen, a usability researcher who writes UX Tigers, reviews the evidence that most people keep the settings a product ships with and treat them as the maker's recommendation. He then argues that AI agents hide their defaults: in the vendor's instructions, in the model's trained habits and in skill files. A skill file is a set of reusable instructions telling an agent how to do one type of task.

• When one large US company enrolled new staff in its retirement plan automatically, participation rose from 37 to 86 percent, although the terms of the plan stayed the same.
• In a study of Microsoft Word users reported by Jared Spool, fewer than 5 percent had changed any setting, so most worked with autosave switched off.
• A default hidden in a skill file cannot be seen when it takes effect. Nielsen says each skill file therefore needs an owner, a version and a review whenever the task or the model changes.
• Nielsen also asks designers to settle an agent's authority before it starts work: which actions it may take, its spending limits, and when it must stop and ask.

A team that builds with agents can give each skill file and prompt its agents run on an owner and a review date, as it would any product default. Applying this to a team's internal build process is an inference and is not the author's claim.

Derived by Working Surface from the article. Source line: Skills therefore need an owner, a version, and a review whenever the task or model changes.

25 September 2026: the defaults, the rejected options and the material an AI can reach decide results before anyone chooses.