Match between the system and the real world

A product should speak the language of the people who use it and present information in the order and form they already know from the world outside the screen.

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The law

A product should speak the language of the people who use it, not the language of the team that built it.

Words, icons and the order of information should follow what people already know from their work and their lives. When the product uses internal terms or an unfamiliar structure, people have to translate before they can act.

Where it comes from

This is the second of Jakob Nielsen's ten usability heuristics, in the form he published in 1994 after analysing hundreds of usability problems found in real evaluations. Nielsen Norman Group's article on Match Between the System and the Real World describes the heuristic and its common violations.

The idea draws on work on mental models and metaphors in interface design from the 1980s: people bring expectations from the physical world and from their own domain, and interfaces that follow those expectations are easier to learn.

What it means for an interface

  • Use the customer's words. Labels should be the terms people search for and say aloud, found through research, not the names of internal systems or teams.
  • Follow real-world order. A form for shipping should ask for address details in the order people write an address in that country.
  • Use metaphors with care. A shopping cart or a trash can works because people know them. A metaphor that only half-fits creates wrong expectations.
  • Respect local conventions. Dates, currencies, units and name formats differ between countries. Match the person's locale.

Examples

Error codes. "Transaction declined: code 51" speaks the bank's language. "Your card was declined because the balance is too low" speaks the customer's.

Navigation labels. A help centre organized by internal department names forces people to know the company's structure. One organized by the tasks people come to do matches how they think.

Calendars. A booking calendar where the week starts on the day local readers expect, with dates in the local format, is read without effort. A different start day causes wrong bookings.

Where it is misapplied

  • Dumbing down expert language. For specialists, the correct technical term is the real-world language. Match the actual audience.
  • Skeuomorphism for its own sake. Copying the look of physical objects is not the point; matching people's concepts and expectations is.
  • Guessing the vocabulary. The team's idea of plain words is not evidence. Test labels with people from the audience.
  • One locale for all. A product sold in several countries cannot match all of them with one set of formats.

Checklist

  • Labels and messages use terms confirmed with the target audience.
  • No internal system, team or code names appear in the interface.
  • Forms ask for information in the order people naturally give it.
  • Dates, numbers, currencies and units follow the person's locale.
  • Icons and metaphors have been checked for the meaning people actually attach to them.

Sources

  1. Nielsen Norman Group. Match Between the System and the Real World (Usability Heuristic #2).
  2. Nielsen, J. (1994). Enhancing the explanatory power of usability heuristics. Proceedings of CHI '94, 152–158. ACM.