There are three main problems with mental models – in particular, when the system:
- Totally lacks a model
- Has a model, but it’s too complex or inconsistent to figure out
- Has a model, but it doesn’t match the user’s model
Joel’s a developer with a real eye for UX. He created Trello; was the major factor behind Excel, Visual Basic, StackOverflow; has authored 5 books; and may be most well-known for his blog, Joel on Software.